I use a similar approach to Guest, David (aka Guest, Guest) but with different tools. I am a Linux user, so the tools I use reflect that but the principles are the same.

I use ffmpeg to extract the camera audio. This is a command line tool and will convert just about anything to anything else. It is available for Windows as well as Linux. There is a GUI called WinFF which basically works as a front end to ffmpeg and enables you to drag and drop the files you wish to convert. I had a quick look at the ffmpeg manual and it looks as if it will convert audio sample rates.

I generally use this for You Tube videos, typically 2 - 4 minutes long, nothing as long as a whole concert. I find a specific point on both the audio recording and the camera audio which I can clearly identify then line those up in Audacity, zooming in as necessary to the get the alignment as accurate as I can. I then play back both together. If the two tracks are accurately aligned, they should sound "as one". If they start to drift apart you will get an echo effect. If you can identify where that starts, you should be able to realign. I've not had that problem with the short videos I make so have never needed to deal with it.

Once I have the camera and actual audio accurately aligned, I then either trim the audio so it starts at exactly the same point as the camera audio or (most commonly as I always start the audio recorder after the camera), I add a short section of silence to the start of the audio track to align its start with the start of the camera audio. Once I've done this I either remove or mute the camera audio and export the audio from Audacity. It's important to export to a lossless format so there is no loss of quality (I normally use Flac, but Wav will do just as well).

My video editor (Open Shot, a Linux tool, though they have plans to port it to Windows and Mac in the near future) allows me to silence the audio in a video track, so I can then add in the separately recorded audio track and line the start of the two tracks up. If you have lined the start of the video and audio tracks up accurately, the two should be in sync. I find it usually works fine but occasionally, they go out of sync when I export the final video, in which case it may be a matter of shifting the audio track very slightly so they are in sync.

Even worse, sometimes they go out of sync when uploaded to You Tube, but there doesn't seem much you can do about that, though deleting your uploaded video and re-uploading it seems to work.

I can't comment on audiodub but I reckon it will largely work in much the same way.