To pick back up on this topic, despite its moderate age:
HTML5 video support is widespread in all modern browsers, and performance is generally stellar, even on mobile. I have recently worked on a project that extensively uses HTML5 video (specifically, in .webm format) to generate broadcast graphics in junction with a messaging pipeline. It was performant and worked exactly as expected, and made for a significant increase in production quality. Since I consider the acceptable latency, responsiveness, performance, and quality requirements for that project magnitudes higher than for AAO, I can only see us benefiting from supporting this.
There's a few conversations to be had concerning how to provide an interface for this in the editor, and how to adjust frame logic to consider videos (do they become their own type of frame? can they be added on top of every frame? can multiple videos be layered on top of one another? etc. etc.), but generally, this is a feature that would be great to have.