The person uploaded it onto Youtube after discovering it. It's mainly to do with the escape scene involving Indiana Jones' friend Jock, the seaplane pilot. Unfortunately it is silent.
When filming the "Jock! Start the Engine!" scene, the production of Indiana Jones and Raiders of the Lost Ark rented a plane from my Grandfathers neighbor (who was a good piloting friend as well). His family was there filming during the trip to Hawaii, and captured a lot of behind the scenes footage of the creation of the small moment. This upload is for educational purposes. It is amazing the ups and downs the whole process took, and it must have taken a very large budget for such a small moment. I will soon have a commentary track with my grandfather to provide more details. I mean really, they wrecked the plane and had to repair it. It's quite the story.