This has already been an issue under CM7. Don't know enough about it to say why it isn't 'fixed' but as far as I know the blade's zoom is done in software so it should be the same result as zooming in with an picture editing program of your choice..
Regarding Youtube HQ: As said, pretty smooth most of the time but not completley lagless from my experience. Just a guess that it has to do with bitrate.
btw: It is KonstaT to whom you should give credit.
Your work has been invaluble in keeping this architecture alive. And for that I give my thanks.