My understanding is that they were aware that the brake system was having difficulties. Perhaps they were filming because they knew it would be a problem if there were strong winds while the brakes were not working.
And yes, in Denmark there are turbines scattered all over the place. They are not all in wind farms like in the US. It is very common to see a single turbine in the middle of a field with no others for miles.
My guess as to what happened was that it spun too quickly to the point that either something excited a natural frequency, or more likely until the force on the blades was too strong causing one to shear off (if you pause right before the accident you can actually see a frame where one blades is warped). Once the first blade moved out of position, the imbalance in the machine would be enough to throw the other blades and bow the driveshaft, which is probably what brings the tower down.
And yes, in Denmark there are turbines scattered all over the place. They are not all in wind farms like in the US. It is very common to see a single turbine in the middle of a field with no others for miles.
My guess as to what happened was that it spun too quickly to the point that either something excited a natural frequency, or more likely until the force on the blades was too strong causing one to shear off (if you pause right before the accident you can actually see a frame where one blades is warped). Once the first blade moved out of position, the imbalance in the machine would be enough to throw the other blades and bow the driveshaft, which is probably what brings the tower down.