"However, we want to be clear that this edition is only free to read, look at and listen to online, and this posting does not transfer any right to download all or any portion of the book The Feynman Lectures on Physics, its photos or tape recordings, for any purpose."
At the time my colleagues and I proposed creating an online edition of FLP, one could only read it in expensive printed editions or in (lousy-looking) pirated PDFs. It was not easy to convince FLP's publisher, which makes a lot of money from FLP sales, that a freely accessible online edition was a good idea! However, we persuaded them, arguing that increased exposure would lead to more, not fewer, book sales. They were still hesitant, but they allowed it, stipulating some conditions, one of which was that downloading/copying the content of the online edition for offline use or distribution would be forbidden. The text you are quoting, written by Caltech's Office of the General Counsel, appears in a footnote on the homepage of The Feynman Lectures Website for this reason.