FYI they have a new method of making these that requires NO royalties to be paid to the movie studios, so they can poke fun at NEW movies and not pay a dime.
The trick is they don't actually play the movie. They record their comments to MP3 and you sync that audio to the DVD that you already own!
It's called Rifftrax, and you can find them online at:
RIFFTRAX. Also, some people have synced the movie and their audio themselves and uploaded the movies to the interwebs. Check your favorite unlegal internet source.
And lots of the old MST3K shows can be found on Netflix.