Paul Levinson, "Light On Light Through" podcast, Episode 93 - http://paullev.libsyn.com/the-selfie-and-marshall-mcluhan .
See, for the things referred to in this episode:

- https://twitter.com/PaulLev/status/452886405262241793 for the picture of McLuhan, Ian McLuhan and him
- http://paullevinson.blogspot.ch/2014/04/tetrad-on-selfie.html for the blogpost about the exchange he had with Ian Bogost about the picture.

See also the http://paullevinson.blogspot.ch/2014/10/photography-flips-into-snapchat.html post where he mentioned this podcast episode.