you need to rewind to 6:51 and wait for icegun
Demo for issue 861 (https://code.google.com/p/hedgewars/issues/detail?id=861). Recorded in 0.9.21.
Fast-forward until the water border is very narrow. I then constantly toggle the auto-camera. You will see the camera bouncing around.
Quick demo showing another bug found, when you crossing a wrap world border which is not a flat surface, also when aiming up using blowtorch you can fall to water through terrain! ;p