Where to download?
If you use Fedora, you can install with yum: yum install xvidcap
If u use Ubuntu or Debian, you can install with apt-get : apt-get install xvidcap
or for advanced user, you can download the source code here.
Below is a video off my desktop I took with xvidcap. On the video, you can see that I was showing off Compiz. :)