Had a 30 min HR interview, rejected for being "underqualified in skills". He asked about what I would to do reduced latency, I said a bunch of stuff off the top of my head related to client-server performance, although I think he wanted more low-level stuff, I wouldn't know since in any case he didn't say anything apart from "ok sure" after presumably not hitting whatever key words he had in front of him. Rather different process from most big tech companies (I was in the hiring committee stage at G**gle at the time, which I ended up accepting) where the actual engineers do the technical screenings and HR just does scheduling and feedback.