For AVC video, you can probably try MKV Cutter. This may require remuxing your video to work with it, and it’s Alpha software, but I’ve had success on small projects: http://www.videohelp.com/software/MKV-Cutter
It’s NEARLY lossless, much like most mpeg2 editors. It only re-encodes the B & P frames orphaned by the cuts, but the bulk of the video is copied untouched.