[Sanddancer]

Mp4 requiring you to hit play is a /feature/ in my book. The fact that animated gifs automatically play has caused more problems, like annoying banner ads, than it's created.

Were this fifteen years ago, I'd recommend that the makers of this format create a proper plugin to handle this format in the interim, but because browser makers are terrified of extra functionality, especially on mobiles, we can't do that anymore.