Well for Ubuntu 11.10 the video editor (converter for me :) ) avidemux is not yet ready. So i though of finding a way to install this may be from an older release of Ubuntu to give it a try.
I chose natty since its more close to oneiric even though oneiric is based on Gnome3 and Natty is based on Gnome2. So i downloaded the debs from https://launchpad.net/ubuntu/+source/avidemux/1:2.5.4-0ubuntu6/+build/2158020
. Well when i tried to install the debs i got a error saying it cannot continue because avidemux-plugins-common_2.5.4-0ubuntu6_i386 is looking for libx264-106. But oneiric comes with libx264-116. So though to give a another try by changing the dependency version in the deb. To edit the deb file i used the scripts at http://ubuntuforums.org/showthread.php?t=636724 thanks to the guys up there who post the bash scripts. I change the libx264-106 to libx264-116 and save the deb.
Well then i again try to install and this time it works, and i open up avidemux and try to convert a video for my droid and it worked great. So i hope this post will help you if your looking for avidemux on oneiric.