To keep this article short, here are the facts. After some tests I took a few underwater photos and shot some videos with this thing and it works! The quality is amazing! This is a product I can recommend without any doubt.
Here's a short video to show the abilities of this bag
But before you hit the buy button and get this thing you should be aware of some things. Handling your camera with this bag is really hard! You can fit 2 550Ds in this bag easily. I think it will work better with bigger cameras. Making adjustments during a shot is almost impossible. So you have to make all your settings first (even zoom and focus) and then start the shoot. Another problem I had was that my 18-55mm kit lens was way to small, so I had to push the tube for the lens against it all the time to avoid filming the inner side of the tube. But with some practice or by taping the tube towards the bag (or using a longer lens) you should get some really nice shots, even if this bag can't replace any professional case for your DSLR.
I can't wait to test this bag on a rainy day...