At the beginning of the video, Seth asks the audience:
You guys know what 'wat' means?"
[He makes a 'wat' sound. He also shows a silly photo of a donkey, perhaps on a boat, wearing some waterproof clothing and holding a cat.]
Someone from the audience replies with some reply which is inaudible in the video.
Seth tells the audience member:
Well, what does "wat" mean? I did a Web search for the query [ wat sound ], but didn't get any answer.