[Vishal Patil]

cant say about 3D for very high level gaming like crysis and not even better than any graphics card.

But ya the 780G will give much better amount of 3D than any existing integrated grahics solution.
As far as videos are concerned, it can play high definition videos too with built in HDMI and DVI support.

Ofcourse the 790 GX with Radeon 3300 graphics is a better option than 780G with Radeon 3200 graphics, else everything is your matter of choice.