I encountered this application and found it quite useful. Siince it's from Hong Kong, it is pretty popular in East Asia region. The description on the website says, "WinMEnc is the free GUI frontend of mencoder. It can convert any media format to the AVI file with the format of mpeg1/mpeg2/DivX/Xvid/H264, etc." Even though it does not have as many options as MediaCoder, I think it is more straight forward to use.
The author does not indicate this application as opensource, but since it uses mplayer and mencoder I am assumung it is. You just need to extract the package or follow the manual installation instruction to use the application. I wonder if it is possible to make a portable version?