I'll keep this as short as possible. The motivation for this video is the fact that most lessons out there require you to perform sweeps in downward/upward motions.
That means, you start either by picking the lower strings or the higher strings. Seldom never are you required to start from the "middle" or the "inside," that is, from the third string, and then go back and forward, each time adding more notes to the arpeggio.
I believe this is a great way to challenge your hands and can also motivate you to come up with more interesting arpeggio-based licks. Here's an example of what I'm talking about:
I call this "expanding arpeggios" and I find it more appealing than just going up and down the strings. Check out this short video where I go further into detail and demonstrate how to use this approach.
By Miguel Marquez