Before I got LEАGUEPASS I used the three sites listed below to stream games. To my experience these were the best websites. At least one of the three always had the game stream. Never missed a game with these…All three can be streamed outside US, I think.
1. FIRSTROW.NET currently here: soccertvlive.net/sport/basketball.html
2. STREAM2WATCH stream2watch.com/
3. ATDHE.NET atdhe.me/index.html atdhenet.tv/
Also… an archive where some of the past great games can be downloaded: http://toums-bball.blogspot.com/search/label/celtics
Keep in mind that these addresses move frequently due to their domains getting seized by the ICE every now and then, so direct links may not work fairly soon. In that case just Google the website names and their new sites will come up.
Hope this is helpful.
If you know any other good streaming sites list them here...