This might not be a fun clip to watch if you don't speak Swedish but to explain the content of the video it is about television licence.
A television licence is an official licence required in many countries for the reception of television (and sometimes also radio) broadcasts. It is a form of tax to fund public broadcasting, thus allowing public broadcasters to transmit programmes without, or with only supplemental, funding from radio and television commercials.
The current licence fee in Sweden is 2076 kr (about $300.00) per annum. The fee pays for five TV channels, 45 radio channels as well as TV and Radio on the Internet. Source: Wikipedia
Some people pay the licence fee, some don't. In this video clip they were saying thank you to Lesli Myrthil, the basketball player, who payed the fee. It took place at NK, one of the most famous malls in central Stockholm.