NBA Live

If you want to watch NBA games live on your computer, the only source of streaming video is a pay service sponsored by the league. Howevever, there are other online sources online that provide video clips of NBA games. 
NBA TV
Go to www.mynbatv.com where you can stream NBA Matches. On the Mynbatv homepage, select "Streamings" from the Main menu. You will be presented with several Matches from the oldest NBA games. You can find even more clips by clicking the Dropdown Streamings on Main Menu or using the search function.

nba live