Its always easy to criticise others and find faults.
What actually cleans the windows? The soap on the mop or the squeeqee ? On wfp what cleanes the windows the brish or the water?
So provided the dirt on the window is agitated enough and theres plenty of soap/liquid on the windows. When the squeegee blades into/around the corners and the windows, this will pull enough detergent to ensure the corners are cleaned and esp if detailing with a scrim.
Personally im not a huge fan of h mans videos or gimmicks. Or swivels or dog tails or the likes,,,ive done my fair share of yrs on trad tools to know its technique and a good rubber in the squeegee that makes the difference on the glass