In the 2011 movie David Tennant played Las Vegas showman and vampire expert Peter Vincent.
In this video Peter begins to tell Charley (Anton Yelchin) and his girlfriend Amy (Imogene Poots) about his experience with vampires but they are interrupted by the recently-turned Ed (Christopher Mintz-Plasse).
Warning this video contains strong language and the video is short in accordance with the copyright holder's wishes.
Apologies if this video does not play in your country. Many thanks to the YouTube account Just Tennant for uploading the video.
Fright Night section of DavidTennantOnTwitter.com