Level 4 can be quite tricky but it is mostly about timing. You need to go to the bottom left of the green zone and then wait for the windmill of blue dots to go past you and then make hold down the right and down button on your keyboard until you have taken the first yellow dot. Then release the right key and press the left. Wait until you have got the yellow dot and then release the down key and put another finger on the up key and you might have to go straight to the left at the end to get to the green zone.
