The OS X version has a 64-bit version. I would assume the Linux version has a 64-bit version. Why not Windows? The last posts I can find on the issue are from 2008. Their compiler wasn't 64-bit or ...
I don't know if this is the right sub-forum (I thought about the programmer's symposium, but this isn't really about programming), so, *shrug*. Also, I've posted on the videolan forums already but ...