Though I've never been a huge fan of the flash animation sites, it looks pretty good.
There was a problem with the login box at first: The username and password prompts didn't appear until I clicked the fields. A non internet-savvy person might not recognize these as login fields.
I really can't tell you why, but the yellow links such as "Home", "3DCity", etc just aren't working for me. Maybe try a different font, or try to match the background color they are over? They're all a constant color, but the image around them (minus the black background) changes. It might even look like a transparent link effect or something.
The one easy fix I picked up was one video has an apostrophe in the title. It was probably escaped in the database, but it is being outputted as \'
You could just stripslashes() on output (Don't do this on input, it opens the site right up for injection).
Also, once I opened the site, FireFox (3.0) went from using 5% of my CPU to about 35%. It dropped back down as soon as I closed the tab. (And FireFox 3 is supposedly to be much better concerning CPU usage than FF2 and IE)
This is probably due to the flash. You may want to have the Flash animation terminate after a few loops (5-10 seconds).
As for the Login page:
Add some vertical padding man! All the input boxes look like they've been flattened on top of each other like pancakes. You may also want to differentiate between the login form and the registration for a little more by enlarging and centering the headers over the respective forms. Also, maybe try a small border of some sort in between?
On the top of that page, it says "Welcome to DostDosti - Dating and Social Networking - Find Friends and Your Love!". I feel like that should fit completely inside of the black box-like thing in the background. For me, it spills over the edge by maybe 5 pixels on either side. There is definitely room, so you might want to decrease the bounds of the text by 10 pixels on either side.
In your user online search page (I'm currently at users_online.php at the bottom), the select boxes for ages are too small. It appears I'm looking for a 13 to 10 year old (But part of the 3 and 0 are cut off) by default. The goal of social networking sites is
Not to attract Child Molesters

This also applies to the home.php search, and probably many others.
In the Search page (search.php), those 3 select elements are too close to each other again. Also, I was very confused at first by the second two. As long as you have all the JavaScript, why not hide the next two while they're not in use?
In home.php, I once again feel like all my text is pancaked together. There is plenty of room here, spread out a little so my eyes don't just from line to line.
It looks like you've been working on this for a long time. It looks very good, but as with many sites there are some small things that can probably be done to improve usability and efficiency.
I hate giving ratings, because it's all relative.
Should I compare your site to Myspace, Facebook, Google, or Joe Shmo?
That is why I refuse to give you a number
I need to get going, but I'll take a look at the other two when I get back.
Bruce