1. A method for sending a message about a new video to a group of related users, comprising: determining that a new video associated with a content creator has been uploaded to a video sharing service; identifying a group of candidate users to receive a message indicating that the new video is available by determining a likelihood that each user in the group of candidate users will engage with the new video is greater than a predetermined threshold; identifying a sub-group of users within the group of candidate users based on relationships of users within the group to each other and based on the determined likelihood of each user engaging with the new video; determining a time to send the message to the sub-group of users; transmitting the message to the sub-group of users at the determined time; determining that the message has been selected by a user device associated with a user of the sub-group of users; and causing the new video to be presented in a user interface including a communication interface associated with the sub-group of users on the user device.