Pearl Abyss. The MMO in question is Black Desert, the firm's maiden offering that is apparently getting ready for public testing in either Korea or Japan.
We say apparently because official details are sketchy. Fan site Steparu.com says that publisher GameOn recently signed a contract with Pearl Abyss, but no dates or territories have been announced.
In terms of the trailer itself, there are plenty of gorgeous environmental fly-throughs, mounted combat, and several stunning character model examples. See for yourself after the break.