We are talking Zebra's here. I have tanks stocked higher than this. I have 50 Rummey nose, 10 Zebra's, 10 Black Mollies, 3 Altums, 5 SAE's and 10 Ammano Shrimp in a 75 gal. This has been setup for over six months. No Problems. I have friends that overstock way more than this and they dont have problems either. It depends on the fish, Filtration, and maintenance. The old rule of thumb about fish inches and gallons is all but worthless IMO.
This guy has a Biowheel and UGF. If he does the maintenance, the Zebra's will do OK. They may not be as happy as theh could be in a larger tank, but what fish is? Even 1 fish in a 100 gallon tank is confined, if you compare to nature.