How to append a 'black' segment without re-encoding?

[dubious buccaneer]

I have a video file encoded with xvid. I would like to append a segment to the end of it, in which there'll just be an all-black frame for a couple of seconds. I want to do this without re-encoding the rest of the video. Can I do this with vdub/mod somehow? Perhaps with another tool?

[LoRd_MuldeR]

Yes, you can do this with VirtualDub! But Avidemux can do it as well.

First you need to create a "black" video, with the same framerate, resolution and format as your existing video.
Then open your existing video in VirtualDub and set Audio & Video both to "Direct Stream Copy".
Now use "Append AVI Segment" to append the "black" video segment you have video created before.
Finally save your video...