This is giving me a headache:

I've got a large (over 8GB) .m2ts file that I need to break down in order to move over to an external drive (FAT32).

Split and Concat won't handle it and tsMuxeR won't work on Snow Leopard. There's a hacked version out there although I've read that it doesn't work properly and I can't seem to find it anyway.

Does anyone know of any applications that might help?

Okay, so I rather easily managed to find that version of tsMuxeR in the end, I was having coicidental connection problems earlier.
For anyone seeking it in the future: instantitunes.wordpress.com/2010/02/26/u...xer-on-snow-leopard/

There are couple of things you might have to do if you experience problems. These are detailed in the readme and discussed further in the comments.

Now, it's finally time to stick it to Lucas with the 'Despecialized' Star Wars edits.

Why didn't split work? It's not 64-bit?

I didn't really persevere with it to be honest. I can't remember exactly what reason it gave.