No, she's absolutely wrong about this. The book is based very closely on Feynman's lectures. He wrote the material and gave the lectures. Other people edited that material into book form, but Feynman did the lion's share of the work.

Saying that Feynman didn't write the book is just dishonest, unless you immediately clarify afterwards that Feynman did indeed write almost all of the material in the book, in something very close to its final form.

You should watch the whole video. From memory, the video author claims that the books are not based directly on the recordings nor on material that Feynman wrote himself, but rather on lecture notes written by another professor who had to cover for Feynman (who is also listed as one of the authors in the book). She also mentions how those lecture notes from this other professor correct some small mistakes Feynman made in some calculations and diagrams from the lecture. Her claim is that Feynman was not the person who actually wrote the text of the book.

Seems she isn't interested in dragging a bit of fame and recognition her way.

It's a low effort way to do that when the other party cannot defend himself.