What to tell friends that want you to transfer YouTube videos to DVD: "try it."
Use the Firefox browser and install the Firefox extension "VideoDownloader." You can find cool FF extensions in Firefox in Tools>Extensions>Get More Extensions.
Then load the YouTube movie click on the VideoDownloader icon and right click to save link as, but rename the link to xxx.flv (it's really Flash). If you know how the play Flash movies, great; others need something like Wimpy Standalone FLV Player. Then use your laptop's video out to play back on a TV.
Otherwise download iSquint/Mac and convert the Flash file to QuickTime. You can use your laptop's video out to play back on a TV. If you want a DVD, get iSquint's $23 sibling VisualHub, which lets you easily convert to many formats. An alternative would be Roxio Popcorn, which also shrinks oversized DVDs down to single layer size. Then use iDVD or another app to finish the job.