Hey all, first post.
I just picked up an FS100 on Friday myself and was having trouble too, so Googled and found this thread, and saw questions but no answers. Bummer!

So I just fiddled around and figured it out.
The files that the camera makes are .MOD, which of course no computer has any idea of what to do with.
Tried renaming them to .MPG. Nope
Tried renaming them to. .MOV. Nope.
Tried renaming them to .AVI. Bingo!
I have the free
VLC player installed and they cranked right up on that after renaming them to .AVI.
Even easier though, just plug the camera into the computer with a USB cable (you
must have the DC adapter plugged in too even on a fully charged battery which is annoying), then open up iMovie (
not iMovie
HD) and it automatically imported all of the stuff on the camera for me. Pretty slick! I've never used iMovie either and it's pretty intuitive and easy to figure out. I was able to select a specific portion of a video, rotate it 90 degrees, and export it as a Quicktime for emailing after like 5 minutes of fiddling. So easy, this is why I switched over to Apple coming up on 2 years ago now! Awesome!
Don't bother with the Canon software. I installed the Mac related stuff but it's basically useless and does nothing, unless it just happened to install a driver that allowed iMovie to see it and import the files off of it. Who knows. I'm planning to junk bin all of the Canon stuff though.
Is anybody a member over here?
http://discussions.apple.com/thread.jspa?messageID=7085835
That poor fellow was completely misled but I don't feel like registering over there too. No need at all to return it.

In case it matters, I have a newer iMac with 10.5 installed, and iMovie 7.1.1. The guy over there was probably correct that iMovie
HD is setup for miniDV and Firewire (it appeared to be quite useless with my FS100) but certainly no need to return it. iMovie not-HD works just fine.
I've been into digital photography for a few years and have a few DSLRs, but the FS100 is my first foray into digital video. It's great! Honestly have no idea how it compares to the other rigs out there, but it's exceeding my expectations as far as quality so I'm happy. Love the small size and compactness. I specificially wanted this one just because it's small enough to squeeze into the lens slots in my DSLR bag. The other hard drive and DVD based ones were all too big and clumsy, so then I'd just end up leaving them at home if they're a pain to carry around and miss stuff. Not with this one though!
- Steve from the DC burbs