So I'm one of those schmucks that posts videos of myself playing along to songs on YouTube. The problem is that I don't really have much in the way of editing software, so I'm stuck with using Audacity and Windows Live Movie Maker. I used to have to sync my audio track with the song and then sync that to the video, and at least one of those always seemed to be slightly off. I finally figured out a way to record my audio and video without any syncing issues by telling my webcam that the bass input is a mic. But I still have to sync that up with the song, and I still have issues. Part of the problem is the lack of precision with Window Live Movie Maker, and the other issue is the lack of precision in my playing. What's the best way to record video and audio while simultaneously syncing it up with a song track? I tried playing the song in Audacity and recording it at the same time, but there was always a slight latency when recording the track.
If I were you I would ditch audacity, as good as it is, and get Reaper. It tells you the latency when you first start it up, and then automatically compensates. Instant non-issue. After that, you can put in Windows Live (which sucks ass) and just zoom in all the way and drop the track with the best precision possible. What I do in Sony Vegas 9 is use the camera audio track to sync up my "good" sound, from my interface. I take the "good" sound and match the peaks up with the peaks of the poor camera sound. Should sound and look natural.
Your setup will work fine. Record using audacity and record using your camera. Import the video into windows movie maker. Import the audio from audacity into windows movie maker. Align the exported mp3 from audacity with the sound from the camera. Mute the camera track. Done.
I use an old skool sync method, like using a film clapper board.....i snap a string before a take, so you get an audio and visual marker which makes syncing a breeze. Let me know if you'd like a demonstration.
You can do latency correction in Audacity, but its not automatic. Its not rocket science though, all you need is a mic and a speaker. You then play something through audacity and record at the same time, measure how far off the two tracks are, and tweak the value in preferences->recording. Well worth doing even if you only use Audacity occasionally.