Pros:
Downloads Youtube videos very fast.
Easy to use because the access icon is always there right on every video page.
Interface is a snap to understand and use.
Cons:
You must very carefully save the link in the email after paying for the upgraded version that does HD. Fair enough, I guess.

This is easy to use, fast, slick interface, powerful.

And it is updated often and quickly after youtube changes their format, so that this addon will work again.

The paid pro version is wonderful for super high videos, well worth the money.