I have another thought, based again on seeing the dripping filament and the smoke in the video that suggests a too-hot temperature. How is the thermistor attached to the hot end? It could be that it isn't quite touching the metal block. That could cause it to read a lower temperature than it should, which would cause the closed loop heater control to raise the hot end temperature higher than it should. Depending on how the thermistor wiring is bundled, starting to print could move the thermistor and further affect how well it is reading temperatures.

With the hot end at a set temperature, you could try tugging around on the hot end wiring and seeing if the measured temperature changes. Ideally the measured temperature would remain steady.