not a daft question at all. A great question. You CAN run an HDMI cable from your Mac to the TV. If the TV supports multiple frame rates, you will get a very nice image. It is very common for people to get a thunderbolt dock with an HDMI port and send that HDMI signal out to a 4K consumer TV.
HDCP is HD Copy Protection – you cant RECORD from this. So the Ultrastudio or any HDMI input will not allow you to COPY the signal (record it onto your computer). A perfect example is this – take a cable box, and send the HDMI out of the cable box to a Blackmagic HDMI to SDI converter, and you won’t get an image (and you can’t record it).
But take that same cable box, and take the analog component outputs (the RCA jacks) and go into a Blackmagic Analog to SDI converter, and you can record all day long without issue.
Rescue 1, Inc.