Building a stand this weekend

[Jaws]

I was just wondering if anyone can see any issues with the following stand I'm going to attempt to build this weekend. It's for a 400G 84"L X 36"W tank. I plan on extending 3 out of 4 of the top plates (the back and two sides of the stand) using 2X12 instead of 2X6 to give me a platform to stand on around the back and sides of the tank. Thanks for your help.

http://m.youtube.com/watch?v=uTmxG4N_V10