Fabulous extension - and I quite enjoy watching how YouTube keeps changing their code to thwart it, and the author usually responds with a fix (auto update no less) within days.
I don't wish to remain on line for the entire time it takes to watch a video, and believe I am well within my rights to download it (which takes very little time) and view it off-line later or when I'm not at my desk, so I don't view this as interfering with anyone's "rights."
