Simply, Download a Real player and surf on a Real player ,it will automatically gives you a option of download audio or video when you play a song . I think you needthis for sites like pz10.com or raag.fm which don't allow to download only allow play songs and this also comes in your browser when ur plugin installed. Some times song ia not full, so just see the size and download it!!! . The quality is not like HQ , it's like recording
Enjoy