I tend to spacebar so that I can have that 5-10 minutes from the flashpoint and apply that time on my Dailies x (3 Characters), HM Fps x (3 characters), and maybe an OP or two depending on day/lockouts.
I don't mind watching them though. Just prefer a quicker run.
Oh, I certainly agree with you here. I know that that time can add up, especially when trying to run through things on multiple 50s. I have 3 50s (on one server that I play) and I know how frustrating it is to get bogged down while trying to run through dailies. Anything that slows down that process is a headache.
But when I actually stop to think about it, what am I really hurrying for? So, I can then log off the game? Especially since there isn't much else to do, beyond dailies and FPs/Ops. Granted I am an altaholic, so it helps me get to those alts without neglecting my 50s, but it's not a huge issue to me one way or the other.
That said, if someone in the group is yelling about spacebar, something I do (along with some of my guildies) is to join in the shouting, all the while intentionally NOT hitting spacebar, just to annoy that person and confuse the hell out of them about the identity of the actual culprit.
Whereas, if you ask the group nicely ("do you guys mind if we spacebar through the cutscenes?"), then I'm much more inclined to go with the group's wishes.