Check the video out again. The damsel in question is not a yellowtail damsel, but a different species. Note how the yellow extends down the tail and onto the belly of the fish on the one Sprung has.
If you can find the same species, they you also might be able to keep it. Just keep in mind that Julian Sprung has a lot of experience and a large tank, so he's going to get a way with a lot more things than most reef keepers.
Ok fine! it is not a yellow tail but a yellow belly or village belle damsel as Julian called them,, and he also said that NOT ALL damsels are bad some are rather benign and you can keep groups of them and they wont bother anybody,, and I understand Julian IS an expert thats why I take his word for it ,,,,But as a first fish for anyone to start out with IMO a damsel is not the worst fish to start with since it is such an easy fish,,some one mentioned a dragonet defiantly not for a beginner ,, tangs unless you have a large tank not for a beginner and even a beginner with a large tank should wait awhile and learn,,,first maybe JKEF should tell us what he wants for fish in is tank and how big his tank is and how long since it cycled etc etc before we tell them they cant have a damsel,,,, MAYBE its the perfect fish for them to start out with ,,,,,,,,,,