Two secrets: my record, over a minute, was when there were a lot of windows open on the computer, and thus the blocks kept stopping, and giving me a chance to move.

The second: for the first fifteen seconds or so as a freebie, move down straight away let all the blocks pass one another and then move the cursor up to the top left. They'll go round a few times before you even get close to them. When one's heading for the top left, move vertically down to the bottom left corner, and hide there for a few more seconds...