: MP4 is a "wrapper." If the video fails to play, it might be due to a specific codec (like H.264 or HEVC) used inside that your player doesn't recognize, though this is rare for standard 720p files. MP4 files explained: How to open and use - Adobe
: MP4 files are widely supported across almost all modern devices, including smartphones, tablets, computers, and smart TVs. 3CdxCwXU_720p.mp4
: This identifies the file as an MPEG-4 Part 14 container. It is one of the most common and versatile video formats because it can store video, audio, subtitles, and images in a single file while maintaining high compression efficiency. How to Use This File : MP4 is a "wrapper