That is a bell 47 with side hoppers, most likely doing mosquito control application. The high pitch whine from this one is a turbine engine conversion. Can't tell from your video if it's piston or turbine but it may be the same.
I have a pretty large head, just dropped over $4I on a HGU 84 and I'm struggling. I went with the XL wide and whilst the interior of the shell is good for size, the opening at the narrow point of the chin is so tight it's jamming in on my jaw line.... any recommendations for a larger lid?