Around here, the ground wires on poles have not been copper for years. They are copper plated steel. Too many fools were stealing the copper ground wires. Just do a search for "killed stealing copper wire"

On the original subject, I have seen two actual pole fires, both in very hot dry conditions. The first I witnessed was late at night, just a bit down the road from the fire station. But the firemen were out on another call. Police came to stop traffic in case something fell into the road. The second was at my home. Wife came home and discovered the power was out. Called in to report the outage. When I got home, the power company was replacing the pole. The very top of the pole had burned through where the fuse/disconnect for high voltage line connects to the pole. When the top fell, it jerked the high voltage drop free from the main line across the road. There is actually a "disconnect" there for this very reason. The line men told me it is common. (actually it was the supervisor, the linemen were actually working) If a bad connection develops, from corrosion etc, things heat up. It only has to get to about 600˚f , about 300˚c to ignite. They actually drive around in hot weather and "shoot" connections with a thermal imaging gun to find bad connections.

The video was indeed a short to ground somehow. The buzz is a sure indicator of that. IF it had not been raining, the pole would have ignited.