You may fit a firewire card in the 66Mhz slot to get extra speed. If drivers for Radeon AIW are released you may use the included firewire in the AGP slot, it should be faster.
But I think that it's like the problem of the chiken and the egg: no drivers appear because there's no soft that uses it and no new apps appear because there's no hardware they can use.
Although BT878/848 are not very useful for video editing, if a new video app is released it should start supporting VHI drivers, then if the software is good enough firewire drivers will be released by somebody because there will be potential users.
On the other hand the first drivers that may appear would be for hard drives etc... so people wouldn't have to wait until video soft is released.
Writing a stack for firewire that works like poseidon with usb is not an easy task...
