The video, which shows the Baywatch star practising a song in bed, has debuted on CraveOnline.
Gary Busey, Christopher Lloyd and Matt Bush will also appear in John Gulager's comedy horror sequel to 2010's Piranha 3D.
Directed by John Gulager from a script written by Marcus Dunstan and Patrick Melton, Piranha 3DD was initially scheduled for a November 2011 release date following its announcement in October 2010.
Hasselhoff plays a lifeguard at a water park which is overrun by genetically-enhanced killer piranhas.
Lloyd will reprise his role as the eccentric piranha expert Paul Scheer as part of a cast which also includes David Koechner (Anchorman: The Legend of Ron Burgundy), Katrina Bowden (American Reunion), Ving Rhames and Grimm's Danielle Panabaker.
Watch a trailer for Piranha 3DD below: