How small can video cameras get? Very small, it turns out. This medical camera from Medigus is apparently the world's smallest, and at 0.99mm wide, I believe it.
The camera is designed to show doctors what's going on inside your body without having to get in there themselves. And they're hoping to make it even smaller, as every little bit counts in such scenarios.
But of course I'm sure we'll see even smaller cameras developed for these purposes get placed in cellphones, where size is also important. Probably not this small, but still.