I want to record an episode of PBS' Great Performances next week which is broadcasting in the Seattle area (I will be there), but not in my home area, so this renders my Slingbox useless for this exercise. I want to minimize the cost of this process, although buying/returning hardware is an option if that's the only way.

The setup will be a Comcast HD cable box with DVR (I already know pulling the DVR recording over to the Macbook is not an option) - I can record either the live stream or replay the recording, but I basically want to capture full HD quality.

I thought of going to Bestbuy and getting another Slingbox to rebroadcast the show on my home network and at least get the video/sound on my laptop, but I don't know what software will record it from there.

If I run a coax cable from the output of the cablebox, is there a USB or Firewire TV tuner I can connect to the Macbook that will act as both a TV and DVR and deposit a playable HD quality recording of the broadcast on my laptop?