I think that’s the fault of whatever app / frontend you are using. On OP’s instance (which is just rendering HTML), and on the community’s instance (using lemmy-ui), this file plays. In both cases, it’s a bog-standard MP4 inside a VIDEO tag with a video/mp4 type. If - for example - you’re using Sync, then that app also can’t play MP4s hosted by Mastodon either.
I don’t know anything about DBZ, but I watch the ‘Pitch Meeting’ for movies way more than I watch the actual movies. The one for Joker 2 is quite fun.