We are going to need, this freeware application ---> Avidemux
Install and lets go.
Load it up and after it loads, click open, browse to where CD 1 is, select it, and then click open.
Sometimes you will see a prompt or two, it's recommended you do whatever the prompts say, I've had a few different ones.
(2 examples of prompts before you load your movie, but most of the time it will just laod it)
Here's it after the prompt it will go directly to this screen.
If no prompt it will load to this screen: as you can see it's only 50 minutes, the first half of our video.
Now click, File, Append, browse to you CD 2, and click open. It will go through the same process as last time.
If you just want a straight merge, leave the settings alone.
Now click Save, now you need to name it including extentsion and pick your save location.
You will now get prompts like this after you save, it's recommended you tick yes if it says smart copy,
Then you will get a quality setting, it's default is 4, but you can play around with it.
After it completes, you should have a perfectly merged (aduio and video) video...test it before you delete you CD 1 and CD 2 files.
Thanks to 'psycopathx' for method below....
Another Method, and probably and easier one, you can decide
You can use VirtualDub or VirtualDub MOD
NJOY, yet again!In virtualdub MOD (the easier of the two...basically it lacks the complexity of the full virtualdub but is dead easy for what we want)
1) got to FILE>OPEN VIDEO FILE and select the first of your .avi files
2) now go to VIDEO and select DIRECT STREAM COPY
3) slide the slider at the bottom all the way to the RIGHT
4) now go to FILE>APPEND SEGMENT and select the second of your files
5) go to FILE>SAVE AS. name and select where to save the file
6) in under a minute you should have a perfectly joined movie