RE: wonder how Helicopters would have turned WWII
A modern day Huey absolutely would of made a difference, even one from the 60's.
I doubt that with the technology of the time a helicopter would of changed much of anything.
The ones in the video show it carrying something in a sling but no rockets or door gunner and without some kind of gun sling you would never hit anything from it anyways.
At most I think it could bring food to the front (if they had any) and ammunition.
As a spotter it could of provided information about troop movements but don't know if they would risk them or how durable they would be to gunfire.