If you have some video that is pretty chunky, you can use this software called RIFE (Real-Time Intermediate Flow Estimation) to add interpolated frames.

Andymation uses this to smooth out some of his flip books – which gives some interesting results.

But it makes me wonder if this is the same technique/engines used by people like videographer guy jones to fix old movies like these:

Or you could go full-on for museum quality restoration like this: