How to turn off iMac display while watching a movie from HD TV?

I just can´t seem to figure this out. All I can think is putting something physically in front of the display, which is just stupid!

Even my MBA and rMBP can do this by dimming the backlight all the way down or just closing the lid and putting them to sleep, the movie will still keep rolling on the HD TV.

Did Apple folk´s super brains miss this feature or are they leaving this out intentionally just to annoy us?

Sorry, but these solutions don´t work. Both screens will be shut off.

trustever said:

This way your screen will be black after a min of not use and which ever you are streeming to the HD TV should keep running..

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It doesn´t.

bmcgrath said:

Turn the brightness down.

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Like I said in my original post, that doesn´t work either. It works with MBA and MBP, but not with iMacs. The brightness won´t go all the way down, not even close. In fact I keep the brightness all the time with my 24" iMac already around 5-10%.

seble said:

Trying using the Shift + Control + Eject trick, this turns off the iMac screen. Not sure of its behaviour when coupled with another monitor though but it's worth a try.

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Would be perfect, but it turns the HDTV off as well.

snkeyez95 said:

I too investigated this. Not possible at the moment. Someone mentioned possibly a terminal tweak, but I found no solution.

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This is so sad. How can Apple miss such a simple feature?

I guess I´ll be throwing a shirt or towel on top of the iMac every time when I´m watching a movie and risk it overheating.

Could Apple give us this feature with an update possibly? It´s a bit ridiculous that I can´t do simple thing like this.

I´m sure they don´t want us either hanging our t-shirts, towels or whatever on top of our iMacs? Or maybe they do, so the iMacs will break sooner and we have to buy newer ones?