Reader Scott Anderson is frustrated with Apple's HD content. He writes:
I rented the HD version of a TV show from the iTunes Store, hooked my laptop to our year-old HDTV, and was told no way, the show can't be played. Same with my Apple monitor. We're pretty furious that Apple did this and that the only workaround is to play in Standard Definition. Sort of defeats the whole idea of having an HD TV.
I understand your frustration, but if you're looking for a direction in which to vent it, I might point it at the movie and TV studios that demand this kind of protection of their content. And while I may not be able to offer you a working solution, I can at least explain what's going on.
In all likelihood, the error you're seeing looks like this photo.
The key acronym in that message is HDCP (High-bandwidth Digital Content Protection). It's an aptly descriptive name. HDCP is a form of copy-protection created by Intel to prevent the copying of audio and video moving across a variety of connections, including HDMI, DisplayPort, and DVI.
It works like so: The device charged with playing the protected content (your MacBook, in this case) sends a scouting message down the line to the receiving device (your TV) to ensure that the TV is HDCP compliant. If it is, the content is encrypted and shoved down the line to be played. If it's not, you get a message like this that informs you that the content can't be played. The HDCP chain can't be broken (so that the data can't be intercepted and decrypted). If it is (or the sending device believes it is, no show for you).
So, the first thing you want to do is check your TV's specifications to ensure that it's HDCP compliant. Given that it's only a year old, I'd be surprised if it wasn't. I have a 4-year-old Panasonic plasma TV that has no problem playing HDCP-protected media. (My 2-year-old Dell monitor, however, throws up this same error when connected to my late-model MacBook Pro via HDMI.)
If the TV is compliant, I'd suggest trying a different cable. My Apple TV would occasionally display this error. When I replaced an old HDMI cable with a new one, the error disappeared. If the TV is compliant and the new cable doesn't work, you could try powering on the two devices in a different order, make the cable connection, fire up the TV, and then boot the Mac (or the other way round).
If the TV isn't compliant, well, I supposed you can take the lofty position that 720p isn't really HD (though it is) as some videophiles claim, and stick with standard definition. That'll show 'em.