well i have a slow internet connection, but if in that video, leading edge flaps (slats) are retracted, then its normal.
No, this was filmed from the flight deck and it was the actual flap lever that was moved.
Upon engaging thrust reversers, LE Flaps go up. This has to do something with the aerodynamic braking sort of thing.
No, this feature is to protect the slats and the LE anti-ice equipment from being damaged by FOD which may be "blown up" by the reverse thrust.