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 you need to import an MP4 into Maya to use as a background for tracing movements: Maya.mp4
Convert your video into an Image Sequence (e.g., JPEG or PNG). Before working with heavy video files, ensure Autosave
MP4 files use temporal compression, which makes "scrubbing" (dragging) through the timeline laggy or inaccurate as Maya tries to calculate compressed frames. If your video won't load, it is likely
If your video won't load, it is likely a missing system-level codec rather than a Maya bug.
In Maya, create an and check the box for Use Image Sequence .
Use the Maya Hardware 2.0 renderer to output a sequence of frames, then compile them into an MP4 using video editing software. Quick Tips for Maya Video Workflow