The way I clean a window is.
I really scrub the frames first, if there is a vent, this is also scrubed until no more dirt comes out of it, this was missed on the video, all you need is for a dribble of dirty water to come out of there and in comes the complaints or the customer will moan to anyone who will listen, if they don't contact you which a lot don't do.
The the glass is cleaned along the top of the pane first, then in sweeping up and down strokes the rest of the window is cleaned.
Next the window is given a rinse, this will show up any grains of dirt which might still be there (if there is dirt particles on the glass then re-clean)
And finally the sills are scrubbed, remember to jet wash the edge of the frame and sill, this is were a lot of dirt hides, then wipe the sills dry with a cloth (only on the ground floor).