Have a look for a program called audacity for ripping stuff from youtube. Can’t say I’ve used it but I’ve heard it might be useful in this situation. There’s not many music videos left on UK youtube now though since they fell out with whoever-it-was
bitTorrent for downloading, if you’ve no qualms about not paying for it. If you’ve an actual Apple iPod, iTunes is the easiest way to buy your music, but there’s plenty of sites out there that are cheaper.