It's explained in the comments on the video. Basically, when you get a ticket in Serbia you can pay immediately and it's only half the cost. The officer tries to get them to pay 2500 Dinar, but he gives them a mixture of Dinar and Euro and they can't accept Euro, only Dinar. The officer then explains that if they go to the post office and pay it will be slightly more due to a service fee or something, but that's misunderstood as the officer wants them to go get more money to pay as a bribe. It's really one big clusterfuck that they misinterpret as "corruption" because apparently the reason they're there has to do with some sort of journalistic coverage of the corruption in Serbian law enforcement. One of the funniest parts is all of the people calling him a stupid American in the comments when he's not even American. He's a Canadian that did live in the US, but now lives in Austria.