It really didn't.

    Unlike the DMCA notice, where WBD used “video” to describe the content, the declaration to the court by Michael Bentkover classifies the infringing content as “summaries of unpublished, character, setting, and plots of a forthcoming series”.

    This distinction may matter, as a summary of a plot may not enjoy the same protection as a leaked video. Copyright generally protects the expression of a work, not the underlying ideas or plot descriptions.

I interpret that as they just didn't like that someone posted the summary, and they are trying to use the DMCA to do a job that wasn't intended by the law's creators.