You mean how I did it? let's assume that the video name is "Youtube - bla bla bla bla" Well, I plugged my n900 via usb and then I chose mass storage, I navigated to where the video is and renamed it to "bla bla", unplugged the device and went to media player on the n900 and the video is still "youtube - bla bla bla bla" so then I cleared the media player cache using xterminal and the video is still name youtube - bla bla bla bla...