davidvdb: Veel is an exception, it's irregular
The modern model of grammar assigns veel to be a quantifier rather than an adjective, given that it is establishing the quantity of books rather than saying anything about the type, size, color, etc of the books. Veel is the indefinite case (that used in this sentence) and vele is the definite case (used when referring to specific books).
Therefore no exception is required, or monickers of "irregular". Personally, I prefer this model. One less rule exception!
I actually don't know that that would make it correct. If it's consistent, I think that it might be b/c of the poor audio (elsewhere on the site it's mentioned how the audio that is used is NOT what the team had originally hoped to use, and that it has problems). I would assume that those problems would be consistent.