Can I Create a Way for Users to Add Fields from the Dashboard and/or create Fields with Same Handle?
I might get you wrong but they must have the option to add as many youtube embed videos as they want?

Isn't it an option to let your client make a new block for every embed and just loop over the blocks they made? 

So your block would look like:

Youtube Video (block)


Youtube embed link
Youtube Description


So they just have to add a block when they want a new one and you can just loop over them like you would with any matrixblock?