Answer
The ball will appear to hover motionless within the falling barrel.
Work Step by Step
When objects are in free fall near the Earth's surface, the acceleration is $g$. The barrel's acceleration is $g$, the person's acceleration is $g$, and the ball's acceleration is $g$. Therefore, the three objects will fall together at the same rate. In the reference frame of the barrel, the ball will appear to hover motionless within the falling barrel.
