He was more than extremely lucky. In the very first frame it almost looked like he had been piggy backing hitching a tow by hanging on to the grab rails of the cab but the turning truck was more than his balance could handle. It is a wonder the tractor's tandems didn't crush him into a greasy spot, but he managed to roll just far enough away to avoid being killed then due to the under tracking of a trailer in turns he managed to escape death again when he was under the center of the trailer axles. Had this been an American made trailer many of their axles have the brake chambers mounted low due to the suspension designs, rock hauling suspensions have the brake canisters and the "S" cams mounted higher up so their could have been many objects to snag him.
He was able to walk away carrying his bike.