The audio is mono. (single channel) please don't be sad.
The anchors are laughing because "the Plague" used to be called beaver fever, beaver fever can also mean that you have a real deep interest in beavers. the word beaver is also a slang term for the vagina. The term beaver fever could be construed as a person who is actively seeking intercourse. because of that the news managers decided not to use the word beaver fever. but the anchors are thinking beaver fever thats why they are laughing.

Beaver fever TV news blooper anchors can't stop laughing.