.mp4 or .m4v or whatever is natively easiest on iPad, into hyperPad as cutscenes, ending credits, pause screen backgrounds, level introductions, loading visuals, etc etc. Wherever they're used, however they're used.
Perhaps even as a background, if you can get it to run smooth and efficiently. But that's just games.
For the interactive entertainment and book crowd (not me, my daughter), it's a whole other level of usefulness. And a place where their viewers need controls like pause, skip, rewind, chapters, etc... which is where this comes in handy:
A while back, Apple finally made it a little easier to handle video with this: https://developer.apple.com/documentation/avkit
A lot less coding and research required to create players, etc. Almost straight forward. But still a very modern apple-ish framework. By which I mean "half arsed, under developed and the result of pseudo commitment to unexplained and uncertain initiatives baked in an oven fuelled by dreams from design-by-committee believers ignorant of quicktime's history."