I don't work at YouTube, but I'd like to play advocate for the devil and see how far I'll get. Premises: 1. YouTube's primary function is entertainment. Many

I don't work at YouTube, but I'd like to play advocate for the devil and see how far I'll get. Premises: 1. YouTube's primary function is entertainment. Many people also derive educational and informational value from it, but that's incidental. Wikipedia and Google News probably serve that purpose better. 2. The most straightforward way to measure how well YouTube serves as an entertainment channel is viewer minutes. There are drawbacks to measuring per-session or per-view minutes (short term outrage spikes can backfire later), so it's better to maximize life-time viewer minutes. These can't be measured directly, but need to be modeled/predicted. But it's a refinement of viewer-minutes, not a fundamentally different metric. Contention: Maximizing viewer lifetime minutes is the best practical way for YouTube to serve it's primary function.