Video and Voice Recording

With all these amazing youtube players (I'm not going to list all of them, as essentially it would be a UU rolecall) I find that they have very seamlessly recorded videos and songs. The best example are Julia Nunes' videos. Regardless of what you think of her as a player, I want to know, is it best to just like mouth the words when you play recording the uke, and then go back over and record. I can't possibly imagine that she for instance plays and sings and records on one track (well, she does, but it seemed impossible with my experiences)! Thanks in advance!

She doesn't lip-synch. She edits all the videos of her takes together.

So for instance, she's singing and playing and that's going into one mic? I just have trouble finding a medium where the instrument is too loud and the voice too quiet.

I know if I could do it, I'd use a separate mic for instrument and voice, or at least a pickup. From what I've seen though, it looks like your typical webcam stuff. For the accompaniment part, you can see here wearing earphones. She's simply singing along to her first recorded track. Multitracking is easy with basic video editing software.

Yeah, that part seems easy enough with headphones. I guess I'll just to double mic. Seems like the best solution. Thanks so far guys!

Well, I can tell you what I've got so far to record with. I have a blue snowball condenser mic that plugs into the USB port of your computer $75 w/stand on Amazon, and I just got a Logitech webcam 9000 pro $69.99 on Amazon. I like this setup because I can record voice and video on the webcam and pull a separate track for intrumental on the snowball. Now if I only had Autotune...LOL!