I can explain! The end of these commercials are winkingly referring to the Dramatic Chipmunk (more accurately, the animal is a prairie dog). The Dramatic Chipmunk (Prairie Dog) was a 2007 viral video phenomenon.
The video, five seconds in duration, feature a prairie dog turning its head to the video camera to music from Young Frankenstein. This is the video:
People really liked the video. They shared it, watched it multiple times, and the video became so popular that Carmax created a campaign inspired by it. (The end.)
Dramatic Chipmunk, Wikipedia
Dramatic Chipmunk, Know Your Meme
Five-second 'Dramatic Chipmunk' video takes the Web by storm, CNet