Noise at high rpm

[radu.postole]

Hello, i attached a clip while towing an inflatable. From time to time while i was turning left or right a noise came up but without affecting power or anything else. Anyone have an ideea what could be and if i have to do some research?

 

[glenn property of pam]

all I can hear is the motor loading and unloading as the person on the tube turns in and out.