Here is how I did it in my game:
Paddle width is about 200px, origin point in its center.
Ball has Bullet behavior, paddle doesn't have Solid behavior.
Result looks something like this:
Red line is the normal ball path (as when using "Bounce off solids").
Blue line is the reflection if you use the formula from that youtube tutorial, which is not very realistic.
Yellow line is the reflection in my game.