Thats not a tech demo, sorry... look for the early CryEngine2 videos, those are tech demos... 

Why is it not a tech demo? It's certainly demoing some tech ;)

 You might want to read up on that demo.  It's not really real time.

LOL, google it and you will find the real tech demos made by Crytek, that video is not real time, is using the engine? yes...

But is rendered frame by frame, print screen, saving the images, and then made a video with them...

ok, my mistake... i didn't realise it was rendered, thought it was in-game So one more time... tech demo from Crytec

Even if it's not real-time, it's still a tech demo, although not a particularly impressive one then ;)

 Ehhh, tech demos are real time:

"A technology demo is a prototype, rough example or an otherwise incomplete version of a product, put together with the primary purpose of showcasing the idea, performance, method or the features of the product."

The key word there is "or".

 If you a going to sell a game engine, are you going to make a video featuring things that can't be made on real time???

Probably not, but depending on the circumstances I might. Maybe you want to show something which isn't yet optimized in a preliminary version, for example.