I suppose you could check the previous screenshot and if it’s the same

Hmmm... this gives me an idea... maybe we could even write a special algorithm that checks whether only certain parts of picture have changed, and store only those, while re-using the parts that haven't changed. It would be a specialized compression algorithm for Moving Pictures. But that sounds difficult, it would probably need a whole Group of Experts to implement. Maybe we can call it something like Moving Picture Experts Group, or MPEG for short : )