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.
MP4 files use temporal compression, which makes "scrubbing" (dragging) through the timeline laggy or inaccurate as Maya tries to calculate compressed frames. 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
If you need to import an MP4 into Maya to use as a background for tracing movements: If it does, switch the image plane's display
A "Playblast" is a way to preview your animation without a full render.
In Maya, create an and check the box for Use Image Sequence .
Many professionals playblast to a high-quality .avi or .webm format and then use Clipchamp or Handbrake to convert it to a standard H.264 MP4 for sharing.