no,In 'theory' - so long as you have the mac drivers (if any) you should be able to capture video via firewire, in the same way you might connect a firewire video camera...
hdv cameras are not supported as video digitiser inputs.
hdv is an mpeg2 format - its used by hidef cameras to get the same bit rate onto a mini-dv tape.The Thomson Grass Valley ADVC-HD50 converter lets you instantly convert uncompressed HD video and audio from HDMI devices to the HDV format
as its mpeg2 - with ibp frames - latency would be horrible - anyway - as the data can only be decoded when all the frames in a group have been transferred. this is up to 18 frames with hdv ( as far as i can remember )
dv does not use interframe compression - hdv does.