Wow I'm very surprised that this old machine can run youtube videos via HD!! I knew not to expect to run any type of hd trailers or anything but I just wanted it to at most run HD youtube videos and it does! I could even end up using this iMac as my main desktop! All around its very fast compared to the 15" 800mhz which has trouble playing standard youtube vids! This 17" seems barely used, the screen is very bright and whites look still very white compared to my 15" iMac that looks more yellowish due to age and its in mint condition! I'm so very happy!! I guess this iMac can run 360p/480p youtube videos until its 720p/1080p officially.