Whichever way you look at it, the signal that comes out of the video card isn't the same signal as went into the capture card, as described above - it enters the digital domain at some point, otherwise you might as well just connect the source directly to the display!
That being said - HDCP complicates matters significantly. I need you to link me to the hardware you are talking about so that I can see exactly what it is that it is doing.
There are 2 possibilities - either the capture and display hardware are directly coupled so that the HDCP License Agreement is satisfied, thus rendering the hardware useless to us, as it will not be possible to get in between the stream to use it (for directing to another MD, recording to HDD, etc); or they have hacked the HDCP encryption to decouple the capture and display endpoints, and are about to get their arses sued off by Intel! I rather suspect the former.
The whole point of HDCP is to secure the channel between the source hardware and the display hardware, making it impossible to intercept the stream and redirect to, say, a recording device. You can of course hack this protection, but anybody who did this in hardware would be rendering themselves liable. This is probably what Thom was referring to.
I suppose it would be possible to "capture" the HDCP stream in raw format just by copying the stream, sending the data (bidirectional) over a TCP connection, then piping the digital stream directly out the HDMI port on the other end - thus allowing the source and display devices to negotiate a valid HDCP connection. However, this still means the signal enters the digital domain, and so renders it particularly vulnerable to a man-in-the-middle attack. I haven't read the HDCP License Agreement, but I would think that Intel probably explicitly procludes that for this very reason - there is no advantage to them in allowing a manufacturer to do that, and plenty of disadvantages. Directly coupling at the hardware layer inside a single PC avoids the man-in-the-middle issue, but also renders it useless to us.
Even if that was allowed, you need to understand that a 1080p HDMI/HDCP stream is raw and uncompressed, and so is approximately 1.5Gb/s, which also renders it useless to us as it is far to high to be practical for piping across a network or storing on disk (note it is encrypted, so cannot be compressed even if you had hardware fast enough)