Well, that easy-as-pie skimmer is not the prettiest, but certainly the most creative one I've seen. I suppose it would work OK in sump. As is mentioned, I'd be concerned about the long-term status of the holes drilled into the jar.
I'd submit that the contact time on this skimmer is not very good so may not be as efficient as others. However, for the overall cost, I suppose you can't beat it.
As Louey mentioned above, if you want a challenge, something that will last and will do an excellent job a skimming, look into a DIY acrylic Beckett-type skimmer. I too took Fergy's classes and can tell you there is a huge difference in quality and performance.
Good luck,
Art