The Joan Baez and Spirit comparisons are just not even close, and the Dazed and Confused comparison is laughable at best. Led Zeppelin evolved from The Yardbirds, which the maker of that video fails to disclose. Dazed and Confused as well as Train Kept a Rollin were both carryovers from the Yardbirds to Led Zeppelin. The other plagiarism allegations involving Dixon and other early blues artists are addressed pretty well in the last paragraph here:
They were lyrical and not musical copies, which is questionable, but the claim that they "ripped off" their early hits is not true.