I have a late 2011 15" MacBook Pro with Thunderbolt/mini DisplayPort. What cable do I need which will transmit both audio AND video?
Dr. Bott have HDMI adapters that can transmit audio as well as video, assuming your MacBook supports it (yours does): http://www.drbott.net/product/5499-MDHD/
Then, get a Thunderbolt to HDMI adapter by Apple which transmits both video and audio. Note that Thunderbolt is backwards compatible with Mini DisplayPort as far as these cables/adapters are concerned.
Monoprice has this adapter. They say it's Thunderbolt compatible, and for $7, I'd give it a try!
As @Asmus mentioned, you have to have a CEC channel or else it messes up your home theater setup. I am experiencing the same problem where I have a Samsung TV, an Onkyo 7.1 Surround Sound system, a 3D Blu-Ray player and then I have XBMC installed on my iMac as an HTPC. However, if I have my iMac plugged in using a Griffin Thunderbolt to HDMI, It causes my whole CEC system to fail.
The only solution I have found (and it isn't cheap) is a USB-CEC adapter. It's pricey at $47 without shipping, but it completely solved my problem - as well as made it so I can use my TV remote to control my XBMC on iMac.
In another, more cheap way to fix the HDMI-CEC to interrupt is to remove pin 13 from the HDMI connector.
I did this on a cheap mini-Displayport adapter for my macbook as i didnt want to spend much cash getting a HDMI-CEC-USB kit. I already had raspberry connected with XBMC on it so I didnt need the TV to control anything on my mac. Just wanted to keep mac not making trouble with the other units.
Fixing this makes the CEC dont send any data on the pin 13 that is making this trouble from keeping the TV not to turn off CEC when dont getting any answer.
Another thread describing the same problem: