The feature lets you “share” messages and videos with your friends. You can invite them via SMS or other chat platforms. Videos shared are playable within the conversation without having to switch back and forth.
In addition, the new update puts tabs on the lower part of the interface the way Apple does with the iPhone operating system. This will ease in access of those options but in general it will break Android overall user interface uniformity. It is possible that Google –Youtube’s parent company- used the name “sharing” instead of chat so as not to cannibalize their messaging platform, Allo. Also, it is possible that WhatsApp’s recent update that enables users to view YouTube videos within a conversation without having to open the video streaming app might have spooked the search giant. YouTube and WhatsApp already have over a billion users, Allo is still struggling to get that kind of a following; it seems like the right move to build such a feature into YouTube. Since users can already share videos via the existing fully featured chatting apps, it will be interesting to see if the “sharing feature” will take off in YouTube.