I have a large avi file (call it M01.dat) 641,000 KB in size which contains a long concert. I only want to keep the last 41,000 KB of it, and discard the rest. I just want to play this section on my computer (using WMP, for example), and not to produce any dvd or vcd out of it.

What software** do I need for this exercise, and how to use this software?

(** preferably freeware)

I appreciate your help.