First playthrough always, and I love it when the pause-menu for a cutscene has the options to not only Continue cutscene and Skip cutscene, but also to Replay cutscene. All it takes is one housemate or parent to interrupt and you can miss key plot or information! I also like "movie players" that are built into a lot of games, that let you review any already-seen scene. Good examples of this are Psychonauts, Metal Gear Solid 3, and Super Smash Bros. Brawl.
On the replay, I tend to skip quite a few. Bayonetta gets an equal mix of "watch" and "skip" from me now I've played it through twice.