Legal Question: Sound Bites

I listen to a Classic Rock radio station in my car from time to time, and their promo spots are full of sound bites from popular songs, movies and TV shows.

So, I understand that they can play a piece of a song… I mean, they are a radio station, you know? But, how can they play sound bites from movies and TV Shows? Do they pay for the right to do that? Or is there a minimum length that they can get away with?

Anyone know?
[sub]Bricker, where are you?!?[/sub]

Quotes from movies are different from songs, which are licensed. The radio stations pay a fee for the right to play music on the air, but once paid, they can use any music they want.

Taking a movie quote is probably considered fair use, since one line is a tiny part of the movie. At the same time, I doubt it’s worth a producer’s while to try to sue over it. In any case, the stations probably don’t pay anything.