Ulrich Kaiser has published "Can Beethoven Send Takedown Requests? A First-Hand Account of One German Professor's Experience with Overly Broad Upload Filters" in Wikimedia Foundation News.
Here's an excerpt:
The first video I uploaded to YouTube promoted the website where my digitized copies of public domain recordings are available to download. In this video, I explained my project, while examples of the music played in the background. Less than three minutes after uploading, I received a notification that there was a ContentID claim against my video. ContentID is a system, developed by YouTube, which checks user uploaded videos against databases of copyrighted content in order to curb copyright infringement. . . .
I decided to open a different YouTube account "Labeltest" to share additional excerpts of copyright-free music. I quickly received ContentID notifications for copyright-free music by Bartok, Schubert, Puccini and Wagner. Again and again, YouTube told me that I was violating the copyright of these long-dead composers, despite all of my uploads existing in the public domain. I appealed each of these decisions, explaining that 1) the composers of these works had been dead for more than 70 years, 2) the recordings were first published before 1963, and 3) these takedown request did not provide justification in their property rights under the German Copyright Act.