I do that already, just not on that site. :)
I use blu-ray dot com to track my BR purchases, but I also just use a word document to track all my buys.
I use DVD Aficionado to track all the movies I own. I also do a word document to track what I own, and another for the ones I own that I haven't watched yet. I tried creating a document to track all of the movies I've seen but never kept up with it. Might have to give this site a try.