Unfortunately the only part that has to be under penalty of perjury is a declaration that "the complaining party is authorized to act on behalf of the owner of an exclusive right that is allegedly in-fringed." So even if these are bullshit, as long as they are acting behalf of the owner of the work they claim it to infringe, they haven't perjured themselves.

And that's for a standard DMCA takedown, which these may not have been. I believe YouTube has their own process separate from the DMCA which may have looser requirements. (They still have to accept standard DMCA takedowns to get the safe harbor protection, but it doesn't mean they can only act on takedowns that are DMCA compliant)