I would say he has Wry Neck going off by the video, which can either be caused by a deficiency in thiamine (B1), neurological damage, or a deficiency in vitamin E. I would start him on high-level vitamin B complex durvet brand, and also get him some vitamin E capsules soft gels, 400iu per capsule. For more information, you can check this link out,
https://www.backyardchickens.com/articles/thiamine-deficiency-in-waterfowl.75690/
The bowedness of the legs may be caused by something else, I think the ataxia like symptoms need to be corrected first before you can consider making a hobble for him.
https://www.backyardchickens.com/articles/thiamine-deficiency-in-waterfowl.75690/
The bowedness of the legs may be caused by something else, I think the ataxia like symptoms need to be corrected first before you can consider making a hobble for him.