I think a black semi-transparent body would be a great addition to your site:) That would allow your graffiti to show but also enable the text to be read:) You could even make the module background semi-transparent (perhaps less transparent than the body though) to keep the flow:)
I would put the birthday feature lower on the page so it doesn't take up such valuable real estate up top.
I love the background image, but the transparency setting makes it difficult to see the "sign up" call to action, the tabs along the top and the site tagline.
Otherwise, a great network that will probably have most success with people watching old videos as the draw in and then getting to know each other in the forum. I would put these features on top with the videos top center and the forum directly under the members feature in the left column.
Make sure you have an analytics program set up so you know if people are watching videos or clicking on member photos/profiles, etc...