If it is my first time though, I'll watch the cutscenes. Requests to skip it are ignored.
If I have already watched it, I'll ask beforehand if people are going to be watching the cutscenes. If they are, I'll just watch it again, otherwise I'll spacebar through it. I find it 10x more boring to spacebar through the conversations only to wait for someone to finish watching it.
^^What Antipodes said. You can discuss it beforehand to see how everyone in the group feels about it. If someone wants to watch the cutscenes, make some popcorn and enjoy them. If nobody wants to watch the cutscenes, everyone can spacebar through them. Cutscenes are one of the very few things that make this game stand apart from other MMOs.
I generally ask e.g. when entering HM Esseles, "Spacebar or popcorn?" Very few people understand what I'm asking, though.
It's called being social. Hell, you can even comment on what's happening in the cutscene. Think of it as your very own version of MST3k. Just, for the love of god, stop screaming "SPACEBAR" over and over again in /p?