Under the Fair Use copyright law, audio can be reproduced for various Preamble Purposes--among them criticism, comment, and teaching. Furthermore, any non-profit educational source may use audio reproductions as well.

I suppose some areas could be debated, but this page definitely contains criticism. There's also commentary (almost one and the same), and the "teaching" aspect is the passing of knowledge.
Now, "non-profit educational source". Depends on how you specifically define it, but I'm not making any profit here.

So anyways, this should clear up any questions or concerns. And, the way I see it, the sound clips can only help the respective artists/companies.

Until the next time, .... keep rockin'!