Yes, they are called by various names: absence seizures or silent seizures.
When it happened. How long it lasted. The type of seizure. How the person felt before and after the seizure. Did they have an aura? Any potential reasons for the seizure. If you are the person who has had the seizure, some of the information can obviously only be got by someone who saw the seizure, so you will need to talk to them. If no one saw it, just record what you know. If you are recording details of another person's seizure, then you will need to get some information from them.
The Sabine women were famous for the legendary seizure of its women.
When you have a seizure, your brain is malfunctioning so you are not conscious of what is going on. It is like the fact that you do not remember being asleep. You can remember dreams when you sleep and you may remember having a dream when you have a seizure. Whether you do or not, you will usually know that you have had a seizure, in the same way that you will usually know that you have been asleep.
I don't know how many people have seizure disorders that are on the autism spectrum. I have when I was experienced it as a small child. There is truly no knowing how many people nowadays in the autism spectrum have seizure disorders.
A one second seizure wouldn't be even noticeable, but seizures can be seconds in passing, and only the person that is having it might know it was happening.
To control anything during a seizure is not really possible, so you could not consciously do it. You could wear some protection in your mouth, but that isn't very practical and you don't know when a seizure will happen. It can also be dangerous having something in your mouth when you have a seizure as you could do other damage, like to your teeth. So there is not very much that can be done to stop yourself biting your tongue when you have a seizure.
People make that claim. I don't know?
If you mean why others might not know you are having a seizure, it could be because it is a very mild seizure that nobody notices. If you mean why don't you know when you are having a seizure it is because maybe you are unconscious or like in a daze or daydream, so you would not know or be aware of anything that is happening to you or around you. Seizures are a temporary disruption of brain activity so you can be affected and not know what is happening. Afterwards you will often know you have had one because of the way you feel or you may realise that you weren't conscious for a few minutes.
sounds like a seizure, but the person would not be able to talk so you don't really have any way of knowing whether they know where they are.
To someone who has not seen a seizure, it can be difficult to know what is happening. There are similarities between some epileptic seizures and other conditions.
seizure (medical) = hetkef (התקף) seizure (grabbing) = tfisah (תפיסה)
Staring at something won't give you a seizure. Flashing lights have been known to cause seizure activity in those who already have a seizure disorder.