YouTube has cut off Keven B. Lee, a video essayist, following the receipt of three copyright warnings.  While many of the video essays included scenes from the original movies, hundreds of hours of work went into the creation of the essays which include considerable original work.  As Matt Zoller Seitz notes in a post on the issue:

Can a critic argue without clips? Sure. Film criticism has largely done without external accompaniments for a century and can continue to do without them. But it's important to note that clips and still frames have been a central part of cinema studies since its inception. Anyone who's attended a film history or theory course knows how valuable they are. Clips often determine the difference between learning something and truly understanding it. They're quotes from the source text deployed to make a case. Take them away, and you're left with the critic saying, "Well, I can't show you exactly what I mean, so I'll describe it as best I can and hope you believe me."

At issue here is not YouTube – they are just following the DMCA notice-and-takedown system – but rather the DMCA system itself, which regularly demonstrates the chilling effect of taking down content without any analysis of whether there is actually an infringement.

Update: Coverage of this story from TechDirt and Ars Technica.