In an interview with GameTrailers' Geoff Keighley, Hideo Kojima clarifies most of the mystery surrounding Metal Gear Solid V.
Kojima begins the interview by revealing himself as Joakim Mogren, the cryptic CEO of the non-existent Moby Dick Studios. Apparently, when Kojima wasn't available to play the part, a Swedish actor was hired to fill in.
Kojima also explains at length the Spike VGAs trailer that seemed to baffle everyone. The ploy was two years in the making, and Keighley was involved from the get-go. It was crafted to serve two purposes -- to create a buzz and energize the community, and to evaluate the FOX Engine.
Additionally, Kojima confirmed that David Hayter was not asked to perform any voice acting in Metal Gear Solid V. This decision was made in an effort to make it feel like "a new Metal Gear game," and that stretches over to voice actors, as well.
Metal Gear Solid V: The Phantom Pain [GameTrailers -- Thanks, Ardent Snow]