Mark Murphy, founder of CommonsWare, talks a lot.
He has delivered countless conference presentations and smaller events, in addition to training that he delivers as requested. Occasionally, these presentations are recorded and the results publicly posted. Here, you will find videos of those presentations. Note that these videos are hosted elsewhere and are uploaded by the event organizers, and so it is possible that they will not always be available.
Skills Matter has links to videos from the 2010, 2011, and 2012 droidcon UK conferences, as well as an "In the Brain" session held at Skills Matters' London offices.