A “barrel roll” is a maneuver that requires thousands of feet to accomplish. It is started, in a jet, above ten thousand feet. The maneuver is a climbing, rolling slowly, inverted at the top and straight and level at the bottom/completion of the roll. The wise pilot starts high and finishes at a safe altitude with plenty of altitude above the ground.
If he hit an oak tree he was doing an aileron roll, where the roll is accomplished in a little more space than the wing span.
Whatever he was doing, he’s lucky to be alive......................