Thumbs up!
I've been buying from Ebay for quite some time (180 successful transactions to date). My luck w/videos has been neither more nor less successful than any other transactions on Ebay. Most of the time I get some great bargains there. A couple of videos were advertised as original but were clearly copies (which is piracy, by the way), but I've never given money for a video and gotten nothing. That says a lot, after nearly three years of transactions.
Bottom line: if you don't mind getting a copy, or a tape that's a little worn, Ebay is a good place to shop for tickling videos. I prefer Magic Touch, myself, but they don't do DVDs. Sigh.