The latest YouTube viral sensation is a song, called “United Breaks Guitars,” made by musician Dave Carroll. No points for guessing which airline’s service is being satirized and attacked in the video, which was viewed 2.5 million times within five days of being posted. As of posting, it had 2,791,539 million views.

See it here:

Here’s what happened in this case.

In the spring of 2008, Carroll’s band, Sons of Maxwell, was traveling to Nebraska for a one-week tour. Passengers on the United flight with Carroll saw his $3,500 Taylor guitar being thrown by United Airlines baggage handlers in Chicago, severely damaging the guitar.

In the months that followed, United didn’t deny that the guitar had been damaged,  says Carroll. But everyone passed the buck, and refused to compensate him.

After nine months of frustration, Carroll decided to air his complaint to the public, via YouTube.

“I promised the last person to finally say “no” to compensation  that I would write and produce three songs about my experience with United Airlines and make videos for each to be viewed online by anyone in the world. United: Song 1 is the first of those songs. United: Song 2 has been written and video production is underway. United: Song 3 is coming. I promise,” he said.

Carroll’s tactic worked. United quickly offered damages, apologized, and promised to use Carroll’s video in training sessions for its reps.

Despite United’s apology, and offer of compensation (which Carroll wants United to donate to charity), Carroll is pushing ahead with plans for the next two videos.  Next time, United may apologize sooner rather than later.

Update: Now the Huffington Post reports that this video has cost United 10% of its market share. Chris Ayres of The Times Online in the U.K. In a column earlier this week, Ayres claimed the Carroll mishap actually cost United $180 million, or 10 percent of its market cap. Ouch.

Julie Power is editor in chief of the Internet Marketing Report and its accompanying blog, www.eIMR.blogspot.com.