one method you can use is with VirtualDub.
open virtualdub up then:
>Choose file - open video file and select the first avi
>Choose file - append video segment and select the next avi
>Choose video: direct stream copy
>Choose audio: direct stream copy.
>Choose file: save file and give it a new name. (add .avi manually)
Boom you're done.
If you wanted to you could change the video quality, by instead of picking direct stream copy choose
>full processing>select video-compression:
divx low motion and give a new bitrate.
Ofcourse this isn't always needed & doesn't really improve the quality (as you have to do it from the start *as in encoding*)
& don't forget to check if lip-sync is ok.
