Make nginx treat another extension as mp4

[khav]

have converted an animated gif animated.gif to an mp4 animated.mp4.I then
rename animated.mp4 to animated.gifv. How can i tell nginx to treat .gifv
files as mp4.

location ~* \.(mp4|gifv)$ {
     mp4;
     mp4_buffer_size 4M;
     mp4_max_buffer_size 10M;
    }

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,270812,270812#msg-270812