You do have to read a bit of documentation, and maybe search out related examples, but once you have found the commands it pretty much runs on automatic.
The wiki has some pretty detailed guides for various things (though maybe not exactly what you are looking to do): ffmpeg.org/trac/ffmpeg/wiki
You talked about splitting stuff up into 10m chunks. Here's an example which gets the first chunk:
Code:
ffmpeg -i input.flv -acodec copy -vcodec copy -fs 10485760 output.flv
It seems to be easier to make commands which take timestamps rather than filesizes, so maybe don't actually use this example at all. This page on the wiki talks about seeking by time: ffmpeg.org/trac/ffmpeg/wiki/Seeking%20with%20FFmpeg
You can do much more if you don't mind doing a little reading. I haven't done much myself; just reencoded stuff to save space on disk.