When doing this lesson, it won't help you if you use a tempo slower than 80 bpm. Learn the pattern first, then gradually increase the speed. When you preform this, keep your fingers close together and as close to the strings as possible.

To increase your dexterity, move up to the next string on the beat. When you reach the top string, come back down while still going up. This will greatly increase your speed and dexterity if you can do this. I like to use a pick while doing this, but you can do it however you want.

If you don't understand this, drop me a line.