PS4 friend lists/online feature

Hey,

So this might be a very poorly worded question but hopefully someone knows what I'm talking about...

My question regards joining a friends game session/being able to join a friends game right from your friends list. If i'm not mistaken, Sony demo'd this feature where a person can go into their friends list, look at the game they're playing and join their session right from that screen. I want to know how in the world does this work?! I only saw the option once... when a friend on my list was playing COD and it had an option to join game. But I don't seem to see that option for any other games...

Also I believe there was a feature where you can actually watch what a friend is playing and jump right into that game...

I know these two features were definitely demonstrated...

Sorry for the horrible description of what I'm trying to ask but can't seem to find the videos online since I'm unsure how to describe this properly.

I'm also curious about how to do this, I've yet to get more interactivity with friends list and multplayer. I've never even joined a party lol.

course on my friends list everyone has "watch dogs" beside their names lol. I have it coming via gamefly to see if how I like it.

Maybe these features aren't available yet on the PS4.

The bit about not being able to join online gaming sessions with friends might be because the room is full or it's only open to private invites from the host. That would be my guess.