Viewing last 25 versions of post by Bendy and Boney in topic Tantabus doesn't support MP4 files, right?

Use HandBrake. It's free and doesn't have any junk (ads, etc) that a lot of free programs have.

https://handbrake.fr/downloads.php

If you need further help, you can try getting in contact with me since I know a decent amount about video/audio formats and converting between them.