He looks like he's trying to quack or take off flying... Ours jiggle like that right before taking off flying (we have Mallards currently)... Is he nervous about something maybe? A nearby male he's showing off for? The neighbors cat?
That's not the typical "jiggling after a bath", that's more pronounced, IMO anyway..
Edit* I consulted DH with the video (I'm the chicken lady, he's the duck man lol) and he says its perfectly normal. It's the duck version of " restless leg syndrome " ha-ha; they're exercising their wing muscles, usually after sitting for a while or when they're young and learning how to use their wings. Just keeping their flight muscles ready to go.