I think their Adsense revenue is primarily pay-per-click whereas banner ads, ads for promoting websites and ad revenue from watching youtube videos is likely a combination of up-front placement + PPC. Coincidentally I'm getting dinner with someone who works in search engine optimisation and marketing tomorrow night, will ask her if she knows about that.
Agree the valuation is good especially considering many of their ventures are loss making / break-even at best such as Waymo.
