Thanks for the additional information. I really appreciate it.
From your description of the behaviors, I can't help but think that what could be going on would be something like focal seizures.
Normally when we think of seizures, we think of the grand mal type, where the whole body spasms and the dog loses consciousness. However, there is another kind, called a petite mal where only one muscle group is affected or the dog exhibits some kind of strange behavior. I suspect this is what is going on with your dog.
The cause of these kinds of seizures can be anything from ingestion of a toxin to low blood sugar (you could try rubbing a little Karo or pancake syrup on his gums to help rectify this if it's the issue) to some kind of organic brain disease or organ disease. Obviously, there's no way to know for sure which is going on with your dog without being able to see him.
Unfortunately often the cause of the seizure isn't found. They call that a "seizure of unknown eitology", which essentially means that yes, the dog had a seizure, but we don't really know why.
Sometimes a seizure can be a one time only episode and no further treatment is needed. However, if he shows this kind of symptom again, you'll need to have him evaluated by a vet. If the seizures continue, they may offer to refer you to a neurologist for more in depth testing. Normally I'd suggest you videotape the episodes so that your vet can see them, but since you've already done that, don't erase it...keep the video in case he has another episode.
Unfortunately, seizures are one of the hardest things to diagnose since there are so many possible causes, but having a video of the episode will help your vet a great deal.
Hopefully this was just an isolated incident, but if he has them again, or if he has any other unusual behaviors for him, then you should have your vet take a peek, just to be on the safe side.
I hope this helps.