It might not be easy, but there must be 'some' way to do it. If there is any detailed explanation of the problem porting to android, I'd like to have a read. Might it be possible to make a plugin act as the companion app? Is Android messaging locked down intentionally to make useful functionality impossible to implement?
It sounds like maybe someone is being stonewalled by Google, due to it's efforts to prevent Youtube downloads. So, maybe if that specific functioality is hard-code disabled, just for Youtube, it could be made to work with every other video host.
As it is, the firefox add-on is spectacular! Thanks for producing it!