United Airlines had an overbooked plane. They asked for volunteers to take a later flight and resorted to dragging a resisting passenger down the aisle. This is the best summing up of all the different clips I've found:

https://www.buzzfeed.com/aliciamelvi...er-the-airline

It seems as if there should be something more to the story than this but I'm not sure there is. United have already put out a press release pretty much confirming why it happened (someone didn't want to be a volunteer so they were forcibly removed from their seat).

Hope this guy sues and wins bigly.