Due to YouTube's special Flash GUI file formats many will not work unless your
downloaded YouTube videos are saved in the new.FLV (flash video) format.
To watch them you will need to install the Media Player Classic. MySpace and
others also have special plug-ins, codecs or special formats which will not
play in Windows Media Player, only in the Media Player Classic. Check each
of the websites for downloads that are required to run their videos and
sound files.
Free-Codecs.com: Download Media Player Classic 6.4.9.0 (1.88Mb Zip) http://www.free-codecs.com/Media_Player_Classic_download.htm