Here is some stills to back that up:
The congressman first grabs the hand of the youth with his right hand
then grabs the camera out of the youth's hand with his left hand
and and continually ask's who are you.and pulls it down to his side.
then next grabs him with one hand by the back of the neck while facing him..
Then pulls him toward him and to his side where he puts his arm around him:
the youth finally pushes away from him and the congressman leaves with his camera (but he must have got it back because the first part of the video is from the camera the congressman grabs and walks away with) 
Whatever else its definitely battery and the kid never lays a hand on the congressman except to push away from him.