There are lots of short cutscenes throughout the Rock the Castrum quest and the next quest: The Ultimate Weapon. (The actual instances involved are called Castrum Meridanium and The Praetorium).
It can indeed be difficult finding a group that lets you watch the cutscenes as they happen. There are not really two hours worth of cutscenes inside the instances though - probably less than one hour all told.
There is one super-long cutscene after you finish The Ultimate Weapon though - but at that point you can ignore the rest of the party.