Yes, If your going to foot break hard you need to straighten your body so you can downpressure your slide foot.
Their speeds are on par for that road. That cop was not that far off. They obviously stopped/avoided the dipshit that swerved. That hard slide is very hard to do controlled as is a hard stop. I ride on the street, frontage road of the highway in town and on the walking path. I ride the speed of cars going downhill and take the bus or push On the board, on the walking path going uphill. The speed limit is 25-40 and that's normal around here to see longboards. that's why we were helmets and strategic placement of armor.
I would ride that street but probably not flat bomb it....