This is a clip from The Mexican, a somewhat underrated movie starring Brad Pitt, Julia Roberts, and James Gandolfini. I say "somewhat" underrated because it's a good movie, not great, but not particularly well edited. It's very complicated - I watched it at least three times before I really understood the plot. Once you get it, it's fun.
The basics are this: Brad Pitt and Julia Roberts are a young couple who can't quite get it together, either in their respective personal lives, or in their relationship. Pitt's in a spot of trouble with the local Mob. Julia Roberts decides to leave him, but inadvertently gets caught up in the same trouble. Said trouble comes in the form of Gandolfini, a gay and somewhat oddly enlightened hit man. As Roberts tells him at one point, "You're a very sensitive person for a cold-blooded killer."
This clip comes near the end of the movie. I love Julia Roberts' monologue here. It clearly makes sense to her, but not to anyone else. Sort of like Sarah Palin!
As a bonus, Gandolfini's answer is actually rather touching and sort of profound. Keep in mind that he is a hit man.
Gandolfini also has one of my all-time favorite quotes in this movie:
"I'm here to regulate funkiness."