The Hangout feature available on Google+ is one of the leading Video Call technology at this day. For Yahoo Messenger Video Call for example, it still only capable to used face to face aka cam to cam process which mean I see you, you see me. It involves only 2 people. Unlike this kind of C2C the Hangout on Google+ is able to simultaneously make video chat with almost 10 people at once. This is something that Yahoo Messenger can’t handled. It might due to this kind of Multiple Video chat need a huge server base. On the contrary the conventional Video Call uses Peer to Peer technology.
The great news is Google Plus Hangout is now available in Gmail. Furthermore, it would replace the Gmail Video Chat.