Apple has one or more pending patents for it's (rather trivial) live streaming protocol and so far only agrees to RAND terms, see https://datatracker.ietf.org/ipr/1142/ I have not seen a confirmation from Apple that it will offer royalty-free licenses if the protocol becomes a IETF standard. That should imho be a requirement for HTML5 adoption.

Also it may be better to adopt another streaming protocol for HTML5 because the Apple's protocol is not suitable for low latency streaming.