Can't play mp4 files

The mp4 files must be maximum 320x240 resolution, any larger and it will tell you that the file is not supported. If the mp4 is created with any profile other than "AVC Baseline" it will tell you the file is corrupted. It also won't do DRM, but I can't remember what, if any, DRM systems typically get used on mp4 files.

You can a free MP4 player program on your computer to play MP4 movies, such as
1. BSPlayer
A free MP4 player for Windows 10/8.1/7, which specializes in playing video and audio in MP4, AVI, MKV, WMV, VOB, MP3, AAC, AC3, WMA etc.
2. Leawo Free Blu-ray Player
Leawo Free Blu-ray Player is an expert Blu-ray media player that could play Blu-ray/DVD discs, folders and ISO image files, videos (up to 4K), audio files on Windows Vista, XP, 7, 8, 8.1 and 10 without any quality loss and dollar.
3. VLC It is a simple and open source cross-platform media player to playback various type of video file. You can also use it to play DVDs, CDs, VCDs, and various streaming protocols.