I asked our mobile support group, as I'm part of the Samsung electronics group for an answer to this question, and here's their response:
Samsung does not recommend using a 3rd party battery for our products because they may cause damage that could potentially void your warranty. You may purchase a Samsung battery here: http://www.samsung.com/us/mobile/cell-phones-accessories
Also, if you'd like more support for your mobile products, you can go to ask @SamsungSupport on Twitter. Hope this helps you!
I've just watched this review http://www.youtube.com/watch?v=jV1lwZREGQU and I don't trust the Youtube crowd there. Will this battery void my warranty with Samsung or not?