SGDK2 does not yet have built-in support for video, but if you just use the audio layer of MP4 (sometimes referred to as M4A) there may be ways to play it. I'm not sure if FMOD supports MP4. The SGDK2 IDE only uses FMOD to preview sound files right now, but really you can use any library you want to play sounds and video at runtime if you have the code to access the library in C#. Just paste the code into your project and write a few lines to link it up to SGDK2's interface and you can use it (that's how FMOD works with SGDK2 at runtime, I've just made that one a bit easier by providing the sound library in that format so it's really easy to import sounds that use FMOD as a player). It looks like the preferred digital audio solution of FMOD is OGG (I don't even know if it supports MP3), but that doesn't limit the kinds of sounds/video that SGDK2 will support, just the kind that you can preview in the IDE.