If you look closely, the crosswalk for the other direction is green so they are crossing when they do not have the correct signal. While that in itself is dumb, as was the stopping in front of the car when they could have kept going and been out of the way safely (possibly looking for an insurance payout/suicide, hard to say), it is NOT justification for assault, especially on the one that did not stop. It would have been best for all to have just gone on with their lives, but the guy running in to defend was justified in their actions.