So you’ve found a great set of video on youtube, and want to download them on your pc just for fun. Here is a simple way to do that. If you change the "Y" in the youtube.com address to "5", 5outube provides links for downloading that video in MP4 or FLV formats.
That’s all there is to it, really—any YouTube video you want to download, just click on the YouTube logo in the lower-right corner of an embedded clip to get to the main YouTube page, then change the "Y" in YouTube.com to "5". Neat stuff, and it worked on all five of the test clips I sent its way.
Have a Happy Downloading