#1
I was wondering what would be the best way to record videos for Youtube with high quality audio. I wanted to be able to have a few videos with a high quality backing track and a recording through my POD as the audio part, so I don't have to use my ****ty camera mic for the audio. How would I do this most easily/efficiently?

Ex: "Ode To Newfoundland" Medley - Chris Feener
AVGN Theme - Same Guy

Something like that basically, as that audio was done with a backing track program and a POD XT direct recording, just not sure specifically how it's done.
#3
I think they recorded the song and filmed themselves recording it and then making the recorded sound and video in sync.
#4
pretty much as gislaune said.

record the audio to your computer as you usually would, but then also video record yourself dong so.

import the audio and video to something like windows movie maker and sync them up. just make sure to mute the audio channel that came in from the camera.
Grammar and spelling omitted as an exercise for the reader.