Record my PS3 through my iMac 27" PLEASE HELP

OK basically i have an iMac 27" connected to my ps3 with the kanex xd, mini usb display to hdmi converter basically. I was wondering is there anyway of me recording my imac's screen whilst i play my ps3, ive tried like screenium etc but every time i switch to the ps3, pressing command f2 its stops the video, please help!!! thank you

That will require a video capture card.

It stops the video because you are switching to a different port on the iMac. Same as switching from HDMI 1 to HDMI 2 to VGA to Component on your regular TV. e.g. switching from satellite to the DVD player to your PS3, etc.

for a cap card though u need an rbg output, all i have is like 2 usb and speakers, very limited, : S imac 27" remember

Then you need to find a video capture card that fits within the iMac limitations.

Here's two options.

Elgato Video Capture

Overview EyeTV HD

ElGato has a pretty active forum also. Would suggest you head there and get some opinions from those using their devices for exactly your intended purpose.