I'm not usually one to say anything about fish and tank sizes because I don't know everyone's situation and plans. Having said that, an emperor and a blue jaw in a 2 foot x 2 foot tank will not be practical in the long run.
As for the trigger acting funny, the video he appears to just be acting like a normal somewhat territorial fish. If you see any other signs come up I would try to setup a quarantine, run all the fish through qt and leave tank fallow. As long as he is eating, looks healthy, etc... I might be inclined to ride it out at this point and focus on feeding and tank stability. Good luck! :)