It's pretty simple. What I do, is say "Sync audio once you click (Insert button name here) in three, two, one, click." I sync the click from the game, with my vocals. Though, for the facecam audio sync, just sync up the audio with your lips. If you're asking how you put in the files, that's a different topic. I hope this helped. ( I just recently got off the forum, now when I see someone in need, I go all super hero, I should really just give up. )

As I said. You record the camera, and then record the audio. Record the video, put everything audio/video wise into a video editor. As I said again, a simple way to sync audio is by saying something to sync it up before you start up the actual video. "Sync the audio, once you click the options button, in 3,2,1 click" as soon as you say click, you click the options button in said game. You need to use a video editor to sync up the audio and video. In the editor, sync up the "Click" to the actual click in the game. I'm planning to do a video series on recording/video production. So, if you still can't understand this, sorry, there is no way I can make it "easier" to understand. Hope this helps.

There's a youtube editor? :O

Anyways, Use camtasia, it supports Webcam recording + screen recording. Well, just experiment.:D

Remember, all of these softwares cost money.
Buy them if you are gonna use them.

What we do for our videos is this. We start both capture devices. We then (depending on what we are recording) use the mouse/controller to hover over different things and say them out loud as we hover over them. For example, in our amnesia videos, we hover the mouse over start, cancel, start, cancel. As we hover over it we say "Start, Cancel, Start, Cancel."

After we do that and get everything recorded, we take our recordings into our editor and then line up so that when we say "Start" the mouse is hovered over start, and then when we say "Cancel" the mouse is hovered over cancel. There isn't any hotkey option to sync up the audio and video. That has to all be done manually.

There is another option, I haven't tried it before so I don't know if it works. But if you can hotkey both recording devices to start when you hit say, F4, then it should start them both at the same time, and you should be able to skip the syncing process. But this will only work if you can set up a hotkey for both of the programs.

Hope this helps!

That is the reason why I never do facecam.xD