I've bought several - but only as others advise, when they half price or near to it - and then they are excellent value.
Even experienced quilters can learn from how others do things, and there are many useful tips and hints, and alternative methods. Yes there is a lot on You Tube, but with the classes you do have access to the teacher with any questions or queries and they are answered in detail quickly plus the subject is dealt with in far more detail, sometimes with back-up PDF info, and I've also discovered some notions I didn't know of, not being a resident of the USA - and also how some teachers use "non" quilty bits & pieces in their work.
It is useful to read the reviews before buying...they are helpful to judge if a particular class is for you or not. I've been pleased with the ones I have.