MP4 is the safest upload format
MOV is common for iPhone, QuickTime, and camera exports, but MP4 is accepted by more social platforms, browsers, editors, and generic upload forms.
When a MOV file will not upload or preview, converting MOV to MP4 is usually the first practical fix.
Before converting
Check the original MOV duration, orientation, and audio. Large iPhone videos, screen recordings, and camera exports can expose sync or rotation issues after conversion.
After converting
Play the MP4 from start to finish. Confirm the audio is present, the aspect ratio is correct, and the upload form accepts the converted file before deleting the MOV source.