The video search engine VideoSurf has released a Greasemonkey script for Firefox that insert a unique "visual summary" strip consisting a frame previews of the video, into the search result page of Google, Yahoo, YouTube and CBS. VideoSurf's advanced algorithms intelligently identify the "most interesting" scenes in each video and creates a nice visual summary that shows you what a video is all about with just a glance. In other words, you never have to be rick rolled again!
I tried to make the script work for other search sites, since Lifehacker reported that it will "most likely" work for any streaming Flash videos. Unfortunately, it doesn't. I couldn't get it to work for other video sites like Metacafe, Liveleak etc. But then, it supports Youtube and Google - that's enough for most of us.