I don't think I've ever bought the extended warranty, and I've bought several electronics in the past 10 years where I could have. I can only think of one item that failed that was covered under a warranty. I happily paid to replace it, since it was way cheaper than what all of those extended warranties would have cost. I have a friend at work who buys them every time. He's used one exactly once, for his kid's DSi. He told me how glad he was that he bought it. I asked him how much he spent on extended warranties and how much they've paid him back. I don't think he's bought one since.
By the way, didn't Best Buy get into some legal trouble with those some years ago? I seem to remember the words, scam, and buyer pressure being used.