| .M4S | Ubisoft | File video | Myst IV: Revelation Save Game File | Myst IV: Revelation | Ubisoft |
| .M4U | Open Source | File video | MPEG-4 Playlist | CyberLink PowerDVD | CyberLink |
| .M4V | Apple | File video | iTunes Video File | Microsoft Windows Media Player | Microsoft Corporation |
| .M75 | Moving Picture Experts Group | File video | MPEG Video File | CyberLink PowerDVD | CyberLink |
| .MCV | Visicom Media Inc | File video | ManyCam Effect File | ManyCam | Visicom Media Inc |
| .MEP | Movavi | File video | Movavi Video Editor Project | Movavi Video Editor | Movavi |
| .META | RealNetworks | File video | RealPlayer Metafile | RealPlayer Cloud | RealNetworks |
| .MF2 | Adobe Systems Incorporated | File video | Authorware Mediator5 Multimedia File | Adobe Authorware | Adobe Systems Incorporated |
| .MJ | Engelmann Media GmbH | File video | MovieJack DVD Ripper File | MovieJack | Engelmann Media GmbH |
| .MJ2 | Open Source | File video | Motion JPEG 2000 Video | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .MJP | LG Electronics | File video | MJPEG Video File | Apple QuickTime Player | Apple |
| .MJP2 | Open Source | File video | Motion JPEG 2000 Video | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .MJPEG | Various Developers | File video | Motion JPEG Video File | Mozilla Firefox | Mozilla |
| .MJPG | Various Developers | File video | Motion JPEG Video File | Mozilla Firefox | Mozilla |
| .MK3D | Matroska | File video | Matroska 3D Video File | CyberLink PowerDVD | CyberLink |
| .MKV | Various Developers | File video | Matroska Video File | CyberLink PowerDVD | CyberLink |
| .ML20 | Apple | File video | Mercury Messenger Video File | VLC Media Player | VideoLAN |
| .MMV | Sony | File video | MicroMV Video File | Squared 5 MPEG Streamclip | Open Source |
| .MOB | Microsoft Corporation | File video | MOBTV Video File | Microsoft Windows Media Player | Microsoft Corporation |
| .MOD | Open Source | File video | Amiga Music Module File | ModPlug Player | Open Source |
| .MODD | Sony | File video | Sony Video Analysis File | Sony Picture Motion Browser | Sony |
| .MOFF | Sony | File video | Sony Video Data File | Sony Picture Motion Browser | Sony |
| .MOI | Unknown Developer | File video | MOI Video File | Capty MPEG Edit EX | Pixela Corporation |
| .MOO | Apple | File video | Apple QuickTime Movie Clip File | Apple QuickTime Player | Apple |
| .MOOV | Apple | File video | Apple QuickTime Movie | CyberLink PowerDVD | CyberLink |
| .MOV | Apple | File video | Apple QuickTime Movie | CyberLink PowerDVD | CyberLink |
| .MOVIE | Apple | File video | QuickTime Movie File | Apple QuickTime Player | Apple |
| .MP21 | AXMEDIS Products and Services | File video | AXMEDIS MPEG-21 Object | AXMEDIS Editor | AXMEDIS Products and Services |
| .MP2V | Roxio | File video | MPEG-2 Video File | Microsoft Windows Media Player | Microsoft Corporation |
| .MP4 | Moving Picture Experts Group | File video | MPEG-4 Video File | CyberLink PowerDVD | CyberLink |
| .MP41 | Microsoft Corporation | File video | Microsoft MP41 Video Data | VLC Media Player | VideoLAN |
| .MP4V | Moving Picture Experts Group | File video | MPEG-4 Video File | CyberLink PowerDVD | CyberLink |
| .MPE | Unknown Developer | File video | MPEG Movie | VLC Media Player | VideoLAN |
| .MPEG | Unknown Developer | File video | MPEG Movie | VLC Media Player | VideoLAN |
| .MPF | Microsoft Corporation | File video | Microsoft Media Package File | Microsoft Clip Organizer | Microsoft Corporation |
| .MPG | Moving Picture Experts Group | File video | MPEG Video File | CyberLink PowerDVD | CyberLink |
| .MPG4 | Moving Picture Experts Group | File video | MPEG-4 Video File | CyberLink PowerDVD | CyberLink |
| .MPJ | Minitab Inc | File video | Minitab Project File | Minitab | Minitab Inc |
| .MPL | Sony | File video | AVCHD Playlist File | CyberLink PowerDVD | CyberLink |
| .MPLS | Blu-ray Disc Association | File video | Blu-ray Movie Playlist Information Data | CyberLink PowerDVD | CyberLink |
| .MPV | Moving Picture Experts Group | File video | MPEG Elementary Stream Video File | CyberLink PowerDVD | CyberLink |
| .MPV2 | Roxio | File video | MPEG-2 Video Stream | Microsoft Windows Media Player | Microsoft Corporation |
| .MQV | Sony | File video | Sony Movie Format File | MPlayer | The MPlayer Team |
| .MSDVD | Microsoft Corporation | File video | Windows DVD Maker Project File | Windows DVD Maker | Microsoft Corporation |
| .MSE | CyberLink | File video | MediaShow Slideshow Project File | MediaShow | CyberLink |
| .MSH | Martin Schweiger | File video | Orbiter 3D Mesh File | Orbiter | Martin Schweiger |
| .MSWMM | Microsoft Corporation | File video | Windows Movie Maker Project | Microsoft Windows Live Movie Maker | Microsoft Corporation |
| .MT2S | Open Source | File video | MPEG-2 Transport Stream File | CyberLink PowerDVD | CyberLink |
| .MTS | Sony | File video | AVCHD Video File | Microsoft Windows Media Player | Microsoft Corporation |
| .MTV | MyMPX.org | File video | MTV Video Format File | ShedWorx Smart Converter | Shedworx |
| .MV | Miva | File video | MivaScript File | Miva Merchant Script Compiler | Miva |
| .MVB | RealNetworks | File video | Multimedia Viewer Book Source File | RealNetworks RealTimes | RealNetworks |
| .MVC | Collectorz.com | File video | Movie Collector Catalog | Movie Collector | Collectorz.com |
| .MVD | Magix Software GmbH | File video | Movie Edit Pro Movie File | MAGIX Movie Edit Pro | Magix Software GmbH |
| .MVE | BioWare | File video | Infinity Engine Movie File | Baldur's Gate | BioWare |
| .MVF | CodeBaby | File video | Production Studio Video File | CodeBaby Production Studio | CodeBaby |
| .MVP | Magix Software GmbH | File video | MAGIX Video Project File | MAGIX Video Pro X | Magix Software GmbH |
| .MVY | Magix Software GmbH | File video | Video Easy Project File | MAGIX Video easy | Magix Software GmbH |
| .MXF | SMPTE | File video | Material Exchange Format File | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .MXM | Next Limit Technologies | File video | Maxwell Material File | Maxwell Render | Next Limit Technologies |
| .MXV | Magix Software GmbH | File video | MAGIX Video File | MAGIX Movie Edit Pro | Magix Software GmbH |
| .MYS | Vineyard Technologies | File video | Vineyard Captured Video File | Vineyard Technologies PC Viewer | Vineyard Technologies |
| .NFV | Netflix | File video | Netflix Video File | Netflix | Netflix |
| .NMM | Microsoft Corporation | File video | Microsoft 3D Movie Maker Recorded Video | 3D Movie Maker | Microsoft Corporation |
| .NOA | Unknown Developer | File video | Japanese Movie Format | Unknown Software | Unknown Developer |
| .NPV | Nexilogic | File video | Pixbend Player Pixbend Media File | Pixbend Player | Nexilogic |
| .NSV | Nullsoft | File video | Nullsoft Streaming Video File | Nullsoft Winamp | Nullsoft |
| .NTP | Open Source | File video | Natron Project File | Natron | Open Source |
| .NUT | Open Source | File video | NUT Video File | MPlayer | The MPlayer Team |
| .NUV | Shedworx | File video | NuppelVideo File | MPlayer | The MPlayer Team |
| .NVC | Nero AG | File video | NeroVision Express Project File | Nero Video 2017 | Nero AG |
| .OGM | VideoLAN | File video | Ogg Media File | VLC Media Player | VideoLAN |
| .OGV | Xiph.Org | File video | Ogg Video File | VLC Media Player | VideoLAN |
| .OGX | Xiph.Org | File video | Ogg Vorbis Multiplexed Media File | Microsoft Windows Media Player | Microsoft Corporation |
| .ORV | Oracom, Inc. | File video | Oracom Video File | Pixtree Technology Movie Viewer | Pixtree Technology |
| .OSP | Jonathan Thomas | File video | OpenShot Project File | OpenShot | Jonathan Thomas |
| .OTRKEY | OnlineTvRecorder.com (OTR) | File video | OnlineTvRecorder Encoded Video File | OTRKeyDecoder | OnlineTvRecorder.com (OTR) |
| .PAC | NetScape | File video | Proxy Auto-Config File | Internet Explorer | Microsoft Corporation |
| .PAR | Siemens PLM Software | File video | Solid Edge Part File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .PDS | CyberLink | File video | PowerDirector Script File | PowerDirector | CyberLink |
| .PGI | Various Developers | File video | Video Recording File | Panasonic DVR Software | Panasonic Corporation |
| .PKD | Power Karaoke | File video | Power Karaoke Project | Power Karaoke | Power Karaoke |
| .PLAYLIST | CyberLink | File video | CyberLink PowerDVD Playlist | CyberLink PowerDVD | CyberLink |
| .PMF | ESRI | File video | ESRI Published Map File | ESRI ArcGIS for Desktop | ESRI (Environmental Systems Research Institute) |
| .PMV | SoftMaker Software | File video | PlanMaker Spreadsheet Template | Softmaker Office | SoftMaker Software |
| .PNS | SourceForge | File video | PNG Stereo Image | 3D Vision Photo Viewer | NVIDIA |
| .PPJ | Adobe Systems Incorporated | File video | Premiere 6 Project File | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .PREL | Adobe Systems Incorporated | File video | Premiere Elements Project File | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .PRO | Adobe Systems Incorporated | File video | Adobe Proto Design File | Adobe Dreamweaver | Adobe Systems Incorporated |
| .PRPROJ | Adobe Systems Incorporated | File video | Premiere Pro Project | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .PRTL | Adobe Systems Incorporated | File video | Premiere Pro Title File | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .PSB | Adobe Systems Incorporated | File video | Adobe PhotoShop Big File | Adobe Photoshop | Adobe Systems Incorporated |
| .PSH | Photodex | File video | Photodex Slide Show | ProShow Producer | Photodex |
| .PVR | Imagination Technologies | File video | POWERVR Texture File | PowerVR SDK | Imagination Technologies |
| .PXM | The Pixelmator Team | File video | Pixelmator Image File | Pixelmator | The Pixelmator Team |
| .PXV | Nexilogic | File video | Pixbend Media File | Pixbend Studio | Nexilogic |
| .QMX | Unknown Developer | File video | Quantum Streaming Video Stream Control Data | Unknown Software | Unknown Developer |
| .QT | Apple | File video | Apple QuickTime Movie | CyberLink PowerDVD | CyberLink |
| .QTC | Apple | File video | Apple QuickTime Support File | Apple QuickTime Player | Apple |
| .QTCH | Apple | File video | QuickTime Cache File | Apple QuickTime Player | Apple |
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