GTo understand why the VT4 will never work in a Sam, realize that the VT4 card itself is a high quality capture card for uncompressed video.
It does not speed up or accelerate this process with GPU or custom chip accelerated fuctions...
The transitions FX, drive controllers and "uncompressed video capability" rely on the host systems CPU power, ram and disk speed. This approach was taken to make us of commodity priced PC hardware and make the VT4 system easily upgradeable via software (unline the vt2000/4000)
The card they sell today is slightly revised version of the Vt2/Vt3 cards from like 7 years ago.
You're thinking about the original Amiga Toaster and Flyer card where the 2 cards worked in tandem, the flyer had 3 scsi controllers, I/0 hardware etc and LOTs of custome chips to make it happen in conjuction with ecs/AGA.
So back then becuase soooo much was done with the Flyer and Toaster 4000 cards, you only needed a 25 mghtz setup.
Really there's soooo much going on when you run the VT5 (compared to the old Amiga versions...) it's crazy, when you think about it. If you're in VTedit it's constanly updating the timeline. Built in realtime Vectorscope... Lightwave multitasks, etc... IVGA can capture video from another PC or MAC via ethernet. All of this is possible due to the use of Windows and muti-Ghz setups.
mine is a dual xeon 3.4 gthz 5 gig ram HP XW8000 setup.
I love the "Amiga Way" of working but so much would have to be added to OS4 from scratch.. When I think about it...well I scratch my head in confusion as to why you'd want to go through the effort?
Get a firewire interface working and that alone will keep you busy and most folks quite happpy.