Maya.mp4 Here

Before working with heavy video files, ensure Autosave is enabled under Windows > Settings/Preferences > Preferences > Files/Projects to prevent data loss if a codec causes a crash.

If your video won't load, it is likely a missing system-level codec rather than a Maya bug. Maya.mp4

If you use an MP4 on an image plane, it may drastically slow down your viewport. If it does, switch the image plane's display mode to None when you aren't actively using it as a reference. codec issues - Forums, Autodesk Before working with heavy video files, ensure Autosave