The David Stillwell talk on online advertising and digital identity comes from a wealth of knowledge, especially concerning how Facebook uses our data. Currently, the speaker works as the Deputy Director of The Pscyhometrics Centre at the University of Cambridge's Department of Pscyhology. Previously, he served as a Research Associate there.
He was educated at the University of Nottingham, where he earned a B.Sc. in psychology, a M.Sc. in psychological research methods and then his Ph.D. in cognitive decision-making. From 2007 to 2012 he acted as the Founder and Developer of the web app myPersonality, which offers psychological surveys and provides feedback for users based on their results. This certainly provides a lot of background for the David Stillwell talk.