I've only taken one class from Craftsy so far (Bead & Tapestry Cuffs with Claudia Chase from Mirrix Looms), but I was very impressed with the format. You pay the class fee, then watch it at your own pace, whenever you want. Pause, stop, rewind - watch part of it now, part of it later. There's no expiration date on your class. Once you've paid your fee, you'll retain access to it indefinitely, so it's easy to go back and re-watch details. You also get access to the teacher via email in case you have questions.
I've just started the "Short Rows" knitting class - that one is FREE.
There's a rigid heddle weaving class, a spinning class, numerous knitting classes... I think I'm going to take the "Shoot It! Product Photography" class next, since I'm always fumbling with my camera.
And the best part? I can take the class in my jammies, a few minutes at a time,to accommodate my short attention span!