Thanks to Hulu, you don't have to stay up past your bedtime on Saturday nights just to catch SNL. You can get all the goodness online for free whenever you feel like it. Wrong! Splitsider points out that some of the best sketches aren't ever posted online for legal reasons.
When SNL is posted online after it airs, NBC usually leaves out one or two sketches because they contain licensed music. Every time SNL uses music in a sketch it does the responsible thing and pays for it.
NBC has to pay a large amount of money to get the rights to use a copyrighted song in a sketch, and that amount increases significantly if that sketch will be posted online (NBC's website and sites like Hulu, which has a contract with NBC). So any part of the show that would complicate negotiations with record labels should it be posted online is removed from the version of the episode on Hulu.