The way these MS points work is that they make you buy 400points at a time which is $5. Then shows cost 160 points each (more for HD). So the way you get these 400 points for free is easy. Join Bing rewards.
If you go to Bing.com and join the rewards program you'll see a way to rack up points everyday.
Once you click the link to add points you'll see them rack up.
Sign in with your Windows live ID. The same one you use with your gamertag.
Then once you start racking up 500 reward credits, you can redeem them for 400 ms points.
It may seem like it will take forever to get to 500, but once you first start out, you get around 300 points just for joining and searching with Bing in about a week. Then you'll be buying shows or renting movies in no time.



