how do I connect my Sony HD video camera to work as my webcam on a mac-mini

I have just purchased a 2.5GHz 4Mb mini-mac. I am using a Samsung HD TV and want to use a Sony HD video camera as a webcam. I have mini-display port, HDMI port and thunderbolt port on the mini-mac. The video camera has mini HDMI port and I have mini HDMI to HDMI cable. I also have HDMI to mini-disply connector. So far I have tried connecting the TV via the HDMI to HDMI cable and the camera via mini HDMI to HDMI/HDMI mini-display convertor to the mini-mac. The TV is showing the display but the video camera (turned on!) doesn't automatically appear or show in either Finder or as available when I am trying to set up Skype. Then tried swapping the two around at the mini-mac with the TV now going through the HDMI to mini-display convertor and the camera going to the HDMI port. Same results as previous set-up.

Can this be made to work? Is there a HDMI to thunderbolt convertor that will work? Is this plug and play technology or are there more complicated set-up [rocedures? Any help much appreciated.