A few hours ago, Hideo Kojima and Yumi Kikuchi presented a new gameplay demo from Metal Gear Solid V at the Tokyo Game Show 2013.
You can see the over 12-minute long video below, or by following this link.
Update: here is the whole presentation in better quality:
In the demo, Snake infiltrates Camp Omega, rescues a prisoner and escapes by helicopter. It shows both new and familiar stealth mechanics, and we also see the tranquilizer gun make a return. The menu screen is also briefly shown.