If you have a video stream that you just want to chop out a bit of video, then VirtualDub or VirtualDubMod will do the job for you and no recompression needed because it will just chop the stream.
You may find that you can compress the stream further with no loss in quality.
VDub can strip out empty frames, reduce the number of keyframes that are often set to 1 every 25 frames can be reduced to 1 every 300 frames or more with no loss.
Furthermore, the program is completely free. Do a search for it on the internet.