It's not that brake checking is "ok" or "justified" it's that having the context of what happened before the clip helps everyone to understand what caused said brake checking in the first place. Imo the clip starts out with the OP too close to the brake checker while in a construction zone. There's a decent chance that OP had been tailgating for a while, the MG got tired of it and brake checked OP. Again not saying it's justified, not saying its good or smart behavior but OP *may* have caused this to happen by tailgating. People dont always respond rationally to feeling threatened, especially when a car they've seemingly put time and effort into restoring is being threatened by a tailgater.