If you're going to get out of your car to yell at another motorist, the one thing you don't want to do is nearly run yourself over. It kind of makes you seem less tough.
Not that getting out of your car and starting an argument is something people should be doing. Unfortunately it happens way too often, and just like in this scenario, it can be because of excessive honking.
In the description of the video, the driver of the dashcam car argues that he couldn't go around the white CR-V because of the double lines and the blind corner, which is understandable.
Meantime, the driver of the Honda, even though he was bothered by the honking, should have stayed in the car. He was obviously in a rush to get "something off his chest", and in his haste, he didn't manage to put the car in Park.
Lucky for him, he only fell underneath the door and not directly under the CR-V, which could have been extremely dangerous had the SUV rolled back even further.