The second video is very suspicious. Cycle shoes attach to the pedal by a click system. When you fall, you usually detach from the pedal by one foot. The other one detaches very dependent on the situation, or not at all. You see this happening: Hesjedal falls, one foot clicks out. His second foot stays clicked in.
After Hesjedal falls, you clearly see the kinetic energy stopped of the back part of the bicycle at one moment. This is because his pedal is still attached to his right foot. After he "clicks out", the back wheel seems to bring the back part of the bicycle in motion. This is unexpected; the back part of the bicycle does not posses any kinetic energy.
Two other options exist for the bicycle movement to occur. 1) the left pedal is fixed to the connecting surface area (road) while the cranks still move. 2) the rear wheel still has kinetic energy (still turning).
The first option simply does not occur, as the right pedal keeps its position relative to the frame of the bicycle (see later frames in the video). The second option would never transfer enough energy to the bicycle as to display the observed bicycle movement. Hesjedal is already lowering speed substantially since he needs to maneuver into the left sharp corner. His speed is 20KMPH max, I'd say probably around 15KMPH. That is by far and large not enough to make the whole bicycle want to spin around hile on the ground.
I think what creates the confusion in the hesjedal video is that he is on a steep slope, but the angle of the video obscures that. That explains both the spinning wheel (caused by the bike slipping down the slope a bit while the wheel was touching the ground, causing the wheel to spin) and his somewhat awkward motion when he stands up.
What makes you say he was on a steep slope? Nothing about the background suggests that this is so (for example, all of the cars in the car park below). Also, if he was on a hill, the bike would have to have somehow had enough angular momentum to spin back up hill, as it appears to do in the later part of the clip.
After Hesjedal falls, you clearly see the kinetic energy stopped of the back part of the bicycle at one moment. This is because his pedal is still attached to his right foot. After he "clicks out", the back wheel seems to bring the back part of the bicycle in motion. This is unexpected; the back part of the bicycle does not posses any kinetic energy.
Two other options exist for the bicycle movement to occur. 1) the left pedal is fixed to the connecting surface area (road) while the cranks still move. 2) the rear wheel still has kinetic energy (still turning).
The first option simply does not occur, as the right pedal keeps its position relative to the frame of the bicycle (see later frames in the video). The second option would never transfer enough energy to the bicycle as to display the observed bicycle movement. Hesjedal is already lowering speed substantially since he needs to maneuver into the left sharp corner. His speed is 20KMPH max, I'd say probably around 15KMPH. That is by far and large not enough to make the whole bicycle want to spin around hile on the ground.