I am not sure if this is a good idea for the obvious reasons.

But,

I am curious, before trying such experiments, couldn't this guy get into his car, drive out of town to a non populated area, and try his experiment there?

He flew into clouds, I dont know what the air temperature there was, or what altitude the clouds where at, but is it possible he could have flown into icing conditions and got ice on his propellers and drone?

I dont know his peak altitude, I dont think he would have got high enough for the air density to have an effect on his propeller density. At higher altitudes, propellers have to spin faster, more drag is induced, etc. Could his battery could have run out quicker?