Well I agree with xtrmx in that I find it very distracting when there is a less than good match between visuals and vocals. Thats not just about match up, but also that the "feel" of the sound and visuals should ideally "match". This is a very subtle thing and not just about straight timing.
The original POV has this problem in spades too, so I guess it's the way it was filmed /edited etc. It may even be the reason it was put together as it was, with lots of cutaways etc.
In terms of post production dubbing, while I understand why PG would want to release a pristine version, I would really prefer "warts and all". These kind of performances are sometimes the best actually - you can hear many examples of this in the Encore Series of CDs. I love the authenticity, it adds to the motion for me!
So I guess it's usually going to be a blend of these two polar 'ideals' on a commercial release, I'd prefer PG erred on the side of authenticity rather than "professional sheen". I think he did this perfectly with Live Blood and Growing Up DVDs for example.
The YouTube clip does sound too clean and is rather at odds with the visuals in places. I find it errs in the "wrong" direction for me, at least.
As far as PG's actual live vocals are concerned, my own empirical take is that they have vastly improved in a live setting since the 70s and 80s. I think he's worked on his vocals over time and added more technical prowess to the natural beauty of those pipes

Thinking back to 1980 - 87 gigs I saw, they could sometimes by quite ropey. Of course, that doesnt mean they were bad - far from it - just more "spirited" than "on the money" note-wise!! He certainly wasn't lip-synching

Recently, his vocals are (more often than not) excellent technically, so perhaps he's just happier to release them as they were. I much prefer this approach.