Currently, we post on wall for #1. when user join, as you can imagine the algorithm would not have much relevant data about user and to get user started it put random but definitely a trending/popular video. #2. when user share a video on joday by clicking share button.
brining relavant content is probably the most difficult problem and its never guaranteed to be accurate... our goal is to fail fast, learn from user behavior to serve more relevant next time...
