what happens when you watch a 1080p movie on a 720p TV?

Hahaha, CHEVY VORTEC MAX, I like your funny sarcastic answer!

But really, I'd think it would be obvious--nothing happens, except that you see the picture in not quite as a good quality! (Oh, and then of course the sound will conform to the quality of that other TV, too, be it worse or better.)

Jokes aside, the TV will scale the 1080p input down to 720p. Usually, the less you scale (up or down) the better, so simply set your source, say a BD player, to 720p output.

All HDTV's will convert the input to it's native internal resolution.

While this will look good on all televisions - the conversion process can introduce artifacts.

In general - it is easier to down-convert than up-convert.

Also - in general - The better brands of televisions (Sony, Samsung, Pioneer) do a better job converting resolutions than the lower end televisions (Dynex, Lutron, Robi, Westinghouse,)

This is why there is no single answer to this question.

My advice: if you have a 720 native television - set all your sources to output 720.

There is a huge debate still raging about this, and people will argue and argue forever.....see both side by side and i doubt you will see the difference.

tv breaks