It must be a very steep hill it rolled down. If the farmer opened the back of the baler on the grade, then yea, it could take off, but to go a long distance, it must have been steep. It could have also fallen off of a trailer being transported out of the field, that could get it going. Most round bales will get a flat spot once they sit for awhile. Our tractor wouldn't start this past winter due to extreme cold, and hubby and I had to roll one in the lot ourselves. Luckily it wasn't too far and there is a slight hill, once we got it going it wasn't too hard to keep it rolling. That should have been on youtube. He called us Ezekiel and Ethel, amish farmers.