as long as the "HD feed" content is in the clear and the capture and device providing the "HD feed" support HDCP, you can record from HDMI, otherwise you would have better luck using the component (analog) connection to record content.
i went through 3 different brand HDMI capture cards in an attempt to try and record/live stream game content from the PS3, not one of the cards would work because of HDCP on the PS3 console (not the game) and the capture card not supporting HDCP.
lots of HDMI capture cards are for sale but the one you want is one that is HDCP supported, just about impossible to find and those that are available range in the upwards price of $1,500 to $3,000.--
Suffolk County NY Police Feed - »www.scpdny.com
PS3 Gaming Feed - »www.livestream.com/elitedata