While saving the videos make sure your force the fps in vdub in both videos to 70 then you should be able to join them

Thank you very much! Works like a charm 😀

Here's what I did:

http://img254.imageshack.us/img254/6826/dosbox05jl2.png

It's working although the framerate is changed to 69.999 after pressing OK.

No out-of-sync-sound, however this video is quite short, I wonder if there's a possibility to experience the sound-video desync when working with long lasting videos?

Sound sync should be okay if you record longer pieces, dunno about chaining together a whole bunch of small ones that all have slightly different frame rates though. But you can always fiddle around with little shifts of the audio.

Tnx!