In the 2011 movie David Tennant played Las Vegas showman and vampire expert Peter Vincent.
In this video after killing Ed (Christopher Mintz-Plasse) but losing Amy (Imogene Poots), Charley (Anton Yelchin) again appeals to Peter for help. Peter, who was orphaned by a vampire, is too frightened to join him, but he does give him some tools.
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