recordmydesktop is buggy & inconsistant at best. Secondly, if I understand correctly, the op is not wanting to record a screencast, but external video. IF a screencast is what the op wants, ffmpeg is the most consistant & quality option. Heres a vid with instructions (for Arch, but same instruction in Ubuntu) http://youtu.be/BuKo0l3ZfEE
As for the best video editing/recording options? Kdenlive & Openshot for editing.
But the best way I found for recording webcam video is to open Kamerka (webcam app) in full screen while recording the screencast with ffmpeg as instructed in the video. I do this all the time & it works great.
Audio? Audacity is the clear winner here.
If you record the audio with the video, you can use kdenlive to extract the audio, then open that in audacity for any editing as the easiest way I know to get a seperate audio version that matches the video