This video is from a frirendly game between Djurgarden and Union Berlin at Tele2 Arena in Stockholm. From what I've heard it all started with Union Berlin supporters hanging at Hammarby supporters pubs (rival team to Djurgarden in the second division), partying with them and also marching the route which Hammarby fans usually do from the city to the stadium before a game. As you see in the beginning of the video, a few minutes before the game some Djurgarden fans put up a Dynamo Berlin banner in the stadium, a team which apparently have some really deep and long history of rivalry with Union Berlin. As I've understood it, it's pretty much like the west against the east berlin.

Anyway, when the banner was put up some Union guys stormed the pitch, and some Djurgarden dito did the same. Bangers, fire torches and chairs where thrown on the pitch. They couldn't get to each other tho, because of the police. The game was delayed 45 mins. It was pretty hectic during the whole game and it was cancelled after 72 minutes when some guys from the Djurgarden stand stormed the pitch, once again. The game ended 1-1. The Dynamo banner was put up and removed in total 3-4 times during the game. The fighting continued outside the stadium with literally 100's of people fighting outside a bar in central Stockholm (according to multiple sources). In total 12 policemen were injured.