I watched both "String Ducky" and "The Problem with Math".

To be honest, I'm not into physics or math at all and only had a 'passing familiarity' with the topic of string theory before and neither of these two videos told me anything about string theory that I didn't already know.

I suppose if one had never heard of the theory, then these videos ought to help give a basic outline of what it is about (which is what I had to begin with).

Btw, I wouldn't say these videos "explain" string theory. The just describe what it kinda looks like.