In my frustration finding a tool that can easily split and join MPEG1 and MPEG2 files without rendering, I stumbled upon this little gem: mpgtx
It is a command line program thar runs on Mac,PC, and Unix systems. There is a GUI for the Mac version available.

So let's say you had a directory of 800 MPEG1 files that have an intro that is about 3-4 seconds long and you want to remove those annoying intros. Just run

On Windows, Unix & Mac run this from the command prompt:

mpgtx -s *.mpg [00:00:3.00-]

The best way to use it though is in a script so you can customize the output name.