Lots of things besides IBD can cause neurological issues. I don't know anything specific about parasites that can, but that does seem like a likely clue to follow up on with your vet. Chemical exposure is another one that comes to mind. How long has he been in your care and do you have any idea what he may have been exposed to before he came to you?

Frankly, I couldn't make out much from the video...but your description certainly sounds worriesome and should be taken seriously, I believe. I wish I had something more helpful to say than "talk to the vet"...but that's all I got.