Given the height of the pitot, it appeared to me that the lanyards attached to the pitot are elasticated, the idea being that if you run towards the rear, stretching the lanyard and then releasing it under tension, the cover will fly off the pitot.
I also noticed a considerable number of edits to the video including possibly a startup failure, access panel left open, remedial work needing to be done on an engine, headsets were unplugged, and then appear later plugged into the same aircraft - headless chickens came to mind. It also looked like the cameras were positioned to evaluate crew performance on multiple aircraft during the event. The sequence of aircraft taxing and taking off, (a) into low cloud, then (b) into a clear blue sky. Was the video constructed from several days worth of activity?
But then I have been known to misinterpret chaotic activity in the past.
IG