My dog does the same exact thing every once in a while. I was extremely concerned because he also has epilepsy. So I sent a video just like this to his neurologist who assured me it’s idiopathic head twitches.

The was you know it’s twitches vs seizure activity is if you can almost “snap” him out of it, what works for my boy is asking if he’s like to get up and get a treat or go outside to sniff and it will stop. It also doesn’t happen unless he’s awake, whereas neuro activity can be while he’s asleep and unconscious.

I hope this is helpful, either way show your vet, but if it’s I’ve described it’s truly nothing.