I'm looking for a free tool to cut MPEG's that are created by recording from a USB cable receiver.

There are a number of applications that do this, and some are free, but most of them take the video and audio decoded and pass them into a codec again to write the final output.

I already have the MPEG's encoded the way I like, so what I need is a tool that can strip the beginning and the ending of the recording before and optionally commercial breaks, by rearranging the data within the file, not re-encoding it.

Now I'm using some old software that came with the cable-receiver, but this actually re-encodes the video when exporting. I've tried VirtualDub but had major trouble getting the audio and video streams to stay in sync (and this was also re-encoding)...

I found this which comes pretty close, but doesn't allow much accuracy in selecting cut positions.