Simply question. I think I´ve seen it in a trailer or was it the xbox one ? 

No feature.

You can streaming you while playing but no vidro chat... only voice or text.

Xbox one you can Skype while playing.

This is one of the features I don't understand why anyone would want this? For one thing it makes your game screen smaller, and if you're playing a game why would you want to take your eyes off the game to look at someone's face that is probably playing a game as well and not making eye contact with the camera. Just seems if it were important enough to do a video chat that it would be a normal skype call without any video game distractions. Just my 2 cents!

I think it would be awesome while you playing MMORPGs :D I do not why I think so ;) 

it's pretty awesome if you play fifa against a friend and see his reaction after you score a goal. that's just one example for why it can be great. 

not sure if it is really necessary if you play and talk to someone who doesn't play but for online matches with friends it's great. will be also nice for co-op and so on...

I guess it depends on the game you're playing huh? Just seems that the majority of games I play I wouldn't want to take my eyes off the screen to look at someone in a video chat. I guess I can see it being useful on a poker game.

The Xbox One has that snap feature that allows 2 apps to run at once and display on one screen. The PS4 can also run multiple apps at once but you'll have to jump between them using the PS button since it doesn't have that snap feature.

i would hate it just because than i'd have to put on pants...

When me and my brother both own an X1, we will snap Skype constantly when playing multiplayer Titanfall and such. It's a much better experience seeing the person you play with/against, that is why I always preferred split screen :).