PAID
Only recommended if you obsess about basketball -
NBA.com - NBA TV - NBA League Pass. It's 55USD/year to follow 1 team, 140 USD for all 30 teams. You can watch matches at any time. Watch only the top plays. As I said it's only for the obsessed like me
Free
I used to watch on
www.nbaonlinestreams.com Video earlier, you can find live streams to every basketball match. The website lists multiple websites to watch each match.
Hope it helps