Want to put videos on your phone? I found a great program to do this:
3GP Converter
Once it is Unzipped, click "Setup.exe"
You may have to put it into English. If not, or once this is done, set it correspondingly to your phone.
If your screen is 240 x 320 (T809, D820, D900) set the setup file to "3GPP+AAC General Settings"
Then hit apply, and run the actual program. You can then drag and drop the file you want converted, and it will convert it for you. I hope I helped Samsung users!
Please post here if you have any more knowledge on this.