Well I have my onpage SEO pretty well sorted out, and I have even got some traffic from G (very little traffic, but still). About AdBrite .. you suggest I should buy ads ? If yes, how much should be payed and how should I evaluate the ROI ? (and what that would be actually..). I'm not clear on what should I expect from the paid promotion.
About user uploading videos...this is tricky,since you would have to do a lot of checking. From what I've seen at other sites that allow this, there are quite a lot of people (webmasters especially) that upload porn to promote their sites/aff offers. For now, I stick to downloading videos, watermarking and re-uploading to youtube. (I don't have a lot of hosting space).
Converter from * to * (pretty much any format from what I know):
ffmpeg. It's wonderfull, I use if for converting to .avi from .flv and watermarking (using overlay text on video). You'll absolutelly love this piece of software

. (Free and illegal in the US because of software patent, but I don't live in the US fortunately

).
So you say you don't have any experience with it.. Well here's some instructions from one of Eli's (bluehatseo owner) readers:
Professional Middleman: Watermarking a video with ffmpeg
I suggest you make a quick sh script to ease the pain of tiping all that shit everytime. I use something like this:
Code:
#!/bin/sh
echo "Transforme: $1.flv in $1.avi :"
ffmpeg -i $1.flv -y -vhook "/home/george/ffmpeg/vhook/drawtext.so -f /usr/share/fonts/truetype/msttcorefonts/Times_New_Roman.ttf -t copyright -T copyrightNotice.txt -x 5 -y 0 -s 10 -c #d8d8d8 -C #000000 -o" $1.copyrightNotice.avi
#-t copyright -T copyrightNotice.txt
ffmpeg -i $1.copyrightNotice.avi -y -vhook "/home/george/ffmpeg/vhook/drawtext.so -f /usr/share/fonts/truetype/ttf-dejavu/DejaVuSerif-Bold.ttf -t www.domain.com -T seeMore.txt -x 5 -y 10 -s 14 -c #ffffff -C #719dc3 -o" $1.avi
rm $1.copyrightNotice.avi
echo "Done."
Also you need to create 2 txt files in the same folder as the sh script,with the name : copyrightNotice.txt and seeMore.txt that should contain the 2 pieces of text to be overlayed (see explanation below) .
This script basicly takes a file's name as input, converts the filename.flv into an .avi file (filename.copyrightNotice.avi) and adds a copyright notice (actually, a disclaimer) on top of the video (in a small font).
The second call of ffmpeg takes filename.copyrightNotice.avi and adds my url (in a big font) at the top of the video.
It then automaticly removes the filename.copyrightNotice.avi as it's unnecessary. The whole thing could be made simpler,but I'm just lazy.
Btw, you can set the color for the text in hex code (just like css).
To use this script, save the code into a file like: zxc.sh
Then,in a command line, call it like this:
This will automaticly take the filename.flv from the current folder and put it trough the process mentioned above.
For more info on the overlay text thing, I suggest checking:
Video Hook Documentation and
FFMPEG: vhook/drawtext.c Source File . ffmpeg also has a module for video overlay, but never used it

.
Btw, I use Linux (Ubuntu Feisty) , what kind of *NIX do you use?
PS: for anyone else interested, ffmpeg is available on *NIX
and Windows.