Firewire should be firewire, so there's no obvious reason it shouldn't be seeing the drive.
I'm assuming that, since you use it for video editing you know the firewire port on the MB is ok (if you haven't tried it with any other devices, do--they can get toasted), and that the FW port on the drive is also good.
If both are fine, I suppose it could be some sort of odd interaction between chipsets, but that sort of thing is exceedingly rare in my experience.
Out of curiosity, when it's attached do you see it either in Disk Utility and/or in the System Profiler? If it's not showing up in either, that sure sounds like a bad port or cable; if it shows in system profiler, then at least you know they're talking to each other. If it also shows in Disk Utility, maybe you can manually mount it from there--I have heard of situations where a drive refuses to mount automatically for one reason or another, though I've never had it happen personally.