Hi Gary,
2 ways actually.
1) Capture HDV via firewire but preview the HDV playback out via the HD Extreme card. Video capture and Deck Control will be all via firewire HDV.
2) Capture via the component HD output of the deck into the DeckLink Extreme. This way, you have the option of capturing to Uncompressed, ProRes, DVCPRO HD etc (if on a Mac). For deck control/timecode, you’ll need to set the VTR to downconvert on the iLink output and use DV Deck Control in Final Cut Pro’s capture settings.
regards
Kristian Lam
Blackmagic Design