How to add a black custom sized border to a batch of digicam videos (avi)?

[extent]

I am joining small family mobile videos (they are now avi format) together which will be added to a final family dvd. depending on which way around I have held the camera/mobile, the avis are either 144x176, or 176x144, or larger but in the same similar fashion. I have tried freevideojoiner(.com)'s program to join the avis together into a single file, but when watching it, I notice that the videos with the second different dimensions are stretched out! Obviously this was because the program set the final file to the dimensions of the first video that was added.

I have been able to correct this problem by adding borders to these videos in virtualdub. I have seperated the videos that I want to add the same borders to, into specific folders, so I am now wondering if virtualdub (or any other program) can do this border adding process to many files, as a batch all at once, instead of having to add/edit them all individually?

thanks for any help if possible