If you've only had him since Tuesday, then he's most likely having relocation stress. This explains the lack of appetite, also babies seldom eat their veggies. The video really does look like he's trying to arm wave. He may be afraid of you, since the situation is new and you are potentially a "huge preditor". Do both arms do this? And his legs? Give him another week or so to adjust. Keep offering him food and give him a
bath daily to keep him
hydrated, otherwise limit the amount you interact with him until he's better adjusted. If you place a shirt you've worn in with him, he can get used to your smell. Make sure there's nothing on the shirt. If his lighting and temperatures are good, and he seems to get worse,then I'd be a concerned.