Have you opened up to your bf about how you actually feel jealous about those things, even if you know it's rather silly?

Like someone else mentioned - is he ok with it if you point out guys that you think are attractive?

If he just likes to comment and truly isn't doing things maliciously.. and if he lets you know in his own way that he thinks you're great, why not make a game of it when you're watching a movie or tv? See if you can guess which of the girls he'll think is the prettiest. Also comment on the men too - then it's all fair.

Like, just using Pirates of the Carribean here - I think Johnny Depp is way hotter than Orlando Bloom. I also think Kiera Knightley is hot. I'm totally straight, but I can easily see that she is. I'd see if my guy could guess which of the two actors I found to be the most attractive... or if he could put all three in order. He'd probably be surprised that I find Keira Knightley more attractive than Orlando Bloom!

Just try to find a way to make it into a positive thing you can do together, as it might help take the jealousy away. And it will make him more aware of the fact that he makes those comments and that you aren't comfortable with him. You both need to be aware of it.