According to Wired's Threat Level blog, in April 2009 the anti-gay-marriage group National Organization for Marriage ("NOM") sent a DMCA takedown notice to YouTube, demanding that it take down a clip from MSNBC's Rachel Maddow Show.  In the clip, Maddow criticizes NOM's "Gathering Storm" advocacy ad, displays short excerpts from the ad and 40 seconds of leaked audition outtakes from the ad, which had been uncovered by the Human Rights Campaign and posted widely on video-sharing sites like YouTube. 

MSNBC apparently sent a counter notice, and YouTube put the clip back up.  Subsequently, Maddow commented on the DMCA takedown request and chided NOM on the air for using copyright law to silence critical commentary:

A cable news segment critical of an issue ad violates the copyright of the organization that made that ad? So you can pay to put it on TV, but I can't address its merits on TV?  Come now anti-gay-marriage people, I know your campaign is about how scared we should all be of gay marriage, but now you're scared of people talking about your stance on it?

Mario Lavandeira, a.k.a. Perez Hilton, sent a DMCA takedown notice to YouTube, claiming that a clip of an advocacy ad entitled "No Offense" from the National Organization for Marriage ("NOM") violated his copyright. In response to Lavandeira's notice, YouTube removed the video.

According to NOM, the ad "highlights the efforts of same-sex marriage activists to silence and discredit pro-marriage advocates, calling them 'liars,' 'bigots,' and worse." The ad, which appears in 30-second and 60-second versions, uses approximately three seconds of footage from Mr. Lavandeira's video blog, in which he calls Miss California Carrie Prejean a “dumb bitch.”   

Mr. Lavandeira also sent a cease-and-desist letter to NOM, demanding that it stop broadcasting the ad on television. NOM's lawyers shot back a response letter refusing his demand on fair use grounds:

No permission was required and no permission was sought from Mr. Lavandeira for use of the approximately three second clip of the video he posted on the Internet of his unjustified and unprofessional diatribe against and personal attack on Carrie Prejean, Miss California, for her response to his question at the Miss USA Competition, April 19, 2009. NOM's use of this three second video clip is protected by 17 U.S.C. § 107 for the purpose of criticism, comment, news reporting, and education as it relates directly to NOM's exempt purpose. NOM's use is not a commercial use, but as an issue advocacy advertisement is protected by the First Amendment to the U.S. Constitution and the fair use doctrine of the Copyright Act.

According to one press account, NOM's lawyers also sent a counter-notification to YouTube, requesting that the video be reinstated. 

In the course of an ongoing lawsuit, Orix Capital Markets, LLC filed a counterclaim against Super Future Equities, Inc., Schumann Rafizadeh, Cyrus Rafizadeh, Houman Thomas Arjmandi, and Keon Michael Arjmandi.  The counterclaim alleged that the defendants set up a website -- www.predatorix.com -- that published false and defamatory statements about Orix.  For example, Orix claimed that the website accused the company of committing tax fraud and being under federal investigation for violating racketeering laws.  Later, Orix filed an amended counterclaim to add a copyright infringement claim arising from Predatorix's re-posting of a page from the Orix website.

The defendants filed a motion for summary judgment, which, in March 2008, the court granted in part and denied in part.  The court dismissed Orix's claims for business disparagement, tortious interference, and copyright infringement (notably, the court found that Predatorix's use of the Orix page was fair use), but found that the defamation claim was sufficient to go to the jury.

In February 2009, after a two-week trial, the jury awarded Orix $2.5 million in compensatory damages and $10 million in punitive damages, split between the defendants, except Keon Michael Arjmandi, who was not found liable.  After the verdict, the parties settled the case on undisclosed terms.  After the settlement, the Rafizadehs published an apology on Predatorix, acknowledging that the postings were incorrect.

After receiving a copyright complaint from the Tribune Company, YouTube took down a video from comedic performance group Improv Everywhere that allegedly infringed copright in a CW 11 (WPIX-TV) news broadcast. The CW 11 broadcast discussed an Improv Everywhere prank and reproduced excerpts from one of Improv Everywhere's own videos.

The original Improv Everywhere video showed an April Fools Day prank in which the group crashed a staged funeral.  CW 11 broadcast a news story about the video under the assumption that the video was a prank on unsuspecting funeral-goers.  In reality, Improv's prank was on any viewer who believed the video to be real.  Improv Everywhere has a detailed post on the takedown.