Actually, WinMencoder is a frontend of Mencoder, I use it a lot for my MP4 player.

Author's webpage here:
http://www.wiscn.com/

and also a direct link:
http://sccnc.onlinedown.net/down/Wis..._199_setup.zip

This link above comes from one of the biggest download site of China, so can be trusted.

enjoy.

BTW: you can setup configuration and save to file for later use.