Details make all the difference in the world.
Lossless implies either full Uncompressed or use of a Lossless codec to temporarily compress.
Either the device outside the Computer needs to perform the Lossless compression for you, or you have to bring the whole Uncompressed thing back across the connection and do it on the Computer.
I don't know of any standalone hardware compression codecs that are "Lossless".. Matrox O2 (PCIe) and some Aja (firewire) come close with near lossless codecs.. but they really aren't needed for PC capture of the Uncompressed stream.. its just too low to worry about.
Several TV Tuner cards for the PCI/PCIe bus have the raw Uncompressed YUV available that
VirtualDub can use, Dell Angel cards, some AverMediaTV cards.. I've been surprised to find that most "Preview" pins on the drivers in DirectShow are Raw.. if
VirtualDub can access them that way you can save the stream direct to hard drives and compress it later with a Lossless encoder. I wouldn't try to do it inbound at the same time with VirtualDub though it might cause frame drops or sound samples to be dropped.
These same cards however are more often used for MPEG2 or higher compression to save TV programs to disk.. which they do quite well.. but if you plan to edit in fine detail.. you probably want the Raw frames first.
If VirtualDub won't capture the Raw feed for some reason, you can resort to GraphEdit and capture and dump straight to an AVI file and then whatever you like with it. Its not elegant.. but you know exactly how the feed was processed.
I've been going the Uncompressed route myself for some time.. but have very little real need for edit or video clean up.. it all gets Compressed to MPEG2 anyway eventually to keep the interlacing. If you really don't care about what you loose by deinterlacing and want really small files for storage.. you can do that too.
But I'm trying to strike a middle ground.
MPEG2 is still 4:2:0 and keeps the Interlacing.. its a tried and true method most people have accepted as good enough for decades.. as long as your not trying to edit or fix something.
Its very true newer ways of compressing have come along.. but they are all Progressive and de-interlace "first" throwing away part of that old school information in the original SD video. There are always new ways of de-interlacing being discovered and do a better job of de-interlacing.. so keeping it leaves the door open to a better transfer to Progressive down the line.
Game capture stuff all seeks to de-interlace and blows that possibility out of the water. I'm not sure if its possible to turn de-interlacing off in a Black Magic Shuttle.
I've played with many buses, PCI, AGP, PCIe, USB
AGP and PCIe are dedicated pipelines, so there is no cross traffic with other cards on their connections.
But you can almost get that with USB.. and for SD its enough even Uncompressed, Raw.. if its pre-compressed to MPEG2 by the device at the end of the USB cable.. its even more convenient.
But all of this doesn't address "good" hardware that handles the signal properly and doesn't skew the hue, skew the brightness or contrast.. or over react to Copyright Protection signals, analog CP or digital CP.
I am far from any kind of expert.. i think I'm, beginning to see what is not worth worrying about.. but I get lots of learning surprises.
As a suggestion though:
Check out the Matrox O2 for the PC or Mac (PCIe or Thunderbolt) or the Aja IOHD (firewire 800 for Mac only) those are standalone codecs and I (vaguely) think they do have an Uncompressed setting on each.
You will be restricted to using XP or OSX 10.8 I believe since neither continued updating their device drivers after they stopped making them.
The down side on both is you will need a pre-amp because they generally have XLR connectors for balanced multichannel audio.. except on the desktop model for the Matrox O2 mini..
They would never, ever compress to Lossless Hufyuv or Lagarith for you.. you would have to do that yourself.. but you would have the raw video.
They are beasts however, and make a lot of heat and howl when running.
The Matrox O2 also has a hardware compression option on any model labeled "MAX" which lets you compress on it inbound, or spin out the compression of raw from the connected PC as a background task.
These were used for field work and TV production work, so be prepared for their size and heft.. it takes quite a bit of dedication to really want to work in Raw with these. The cabling overhead is large.