In Kawa's case it looks like the prop was feathered back so he had much less drag than some of us have to deal with but regardless, I agree with others, starting a retractable propulsion system over some unknown landing location can lead to anything from minor scratches to broken glider and injured pilot. NTSB accident query here in the States lists several such cases where the engine did not work. In some cases it appears the pilot became distracted by the engine failure and either crashed into trees or cartwheeled the aircraft. So the other important thing here is to fly the airplane ..and not a bad thing to say out loud.