Ah, those would be Dress
They are worn with Formal Dress, Dinner Dress, Full Dress, and Service Dress uniforms, and the overcoat and all-weather coat during official ceremonies, occasions requiring special honors, social functions (as directed), all social functions where a formal invitation has been extended, and at all times by aides to foreign representatives.
The photo I posted is the Service
Aiguillette, worn during less formal occasions (the officer is wearing the Service Dress uniform).
As to why he was wearing it: The Aide to the President, Aide to the Vice President, aides at the White House, and officers designated as aides to foreign heads of state wear aiguillettes on the right shoulder; all others on the left shoulder.
I lift things up and put them down.