I have an
AverMedia Capture card and it works well with a few caveats.
There is no loop-through on the card like the
Blackmagic Intensity Pro. That means that the only way to view what you have plugged into it is through it's capture/monitor application on the PC.
At first this seemed like no big issue for me as I already have my xbox hooked up to my computer monitor and use a video switch to go back and forth between it and my pc. Only issue is that there is a pretty noticeable lag. 400 to 500ms I would say. There is no way you can play W@W, MW2, BOPS, etc. this way. You just die a lot.
The only solution was an active(powered) HDMI splitter. I split the signal from my xbox with one going to the capture card and one going to my computer monitor. I have a second monitor on my PC so I use that to fire up the capture software. The splitter does introduce a perceptible amount of noise into the image which is not show stopping, but it is undesirable.
So now I could capture and play at the same time.
On to the next issue. The Avermedia capture app is bit rate capped at 15K. This wasn't fast enough for full detail. I was not able to get the cards signal in any other app such as Premiere or Virtual Dub so I was stuck with their app. It also uses some bad compression settings that you can't change. So the resulting video had compression artifacts and other issues.
The solution was simple since the capture app monitored uncapped and uncompressed. I use FRAPS to capture the AverMedia window. FRAPS works great at this and has a lot of options for capturing. It has a great native format that while big, keeps a lot of detail around for when you recompress.
So the AverMedia is a lot cheaper initially. But after buying a splitter and FRAPS, it gets closer to the BlackMagic price. I have not used a BlackMagic so I cannot speak to how well it works, and how its software is. But on the face of it it would eliminate the splitter and potentially FRAPS depending on how its sofwtare works. I know it also will work with Virtual Dub, Premiere, Vegas Pro, etc.
I have heard of some compatibility issues with the Blackmagic and X58/Core i7 based computers though which is why I have not purchased one myself.
P.S. You'll need a fast disk to record HD video. I find that to record video from the XBox with the AverMedia and FRAPS, I need to be able to sustain around 110 MBytes/s. A single disk will not do this. I run 4 disks in a RAID 0 array. A 2 disk array should work though.