A user will have to use the accustomed @ sign before tagging his friend so that s/he can be notified about the post s/he is tagged in.
On the other hand, group video calls will function just like you would expect. As many as 16 people can join a specific video call group and everyone will have this option of joining the call or connecting only through voice call. Moreover, as soon as the video call will begin, everyone in the group will be sent a notification.
Both these features will be rolled out to everyone within next few weeks.
Image Source: TheNextWeb