If the policeman is charged with anything, his defence team will use the fact that he was drunk and obstructing the police. They will allege he had a long history of alcoholism, and that he was drunk, was one of the reasons he fell so easily. If the prosecution use the video of him being pushed over, then the defence team will use the video of him drunk in the middle of the road blocking a police van, despite being asked to move. They will also jump on the fact , that it was not the first time he had obstructed the police, and may have possession of more videos of him.
The bummer about videos being used against the policeman, is that his defence can do the same to defend him.
Just pointing this fact out.