I've found a cumbersome, but effective work-around until AVS can fix their screen capture sync issue.
I use CamStudio because of it's flexibility, using their "Lossless codec 1.5" and audio @ 44.1khz/16-bit sound. I use full screen capture (1600x900) which is an easy 720 HD conversion.
I record a screen capture video. I just did one of 16:18.933 duration. It was badly synced, off 24 seconds at the end. I suppose the longer the video, the worse the syncing.
Using the AVS audio Editor, I extracted the sound to mp3. The sound was 15:55.040.
The ratio of video to sound is 102.5% (almost exactly. So in the Audio Editor I increased the "Rate Change" to 102.5%. This gave me an mp3 of 15:55, not even .5 seconds off the video.
I put them both in the AVS Video Editor, mute the audio track on the video, and...Shazaam...a properly synced screen capture video.
I've done this twice now with great success. Cumbersome, but effective.
But I do hope AVS gets this fixed. But in fairness to them, seems every screen capture software has a sync problem.