The free ride may ending for people who rip YouTube music videos to MP3s through youtube-mp3.org and similar sites.

YouTube's lawyers have sent cease-and-desist letters to the sites, threatening “legal consequences” to those that don't comply, TorrentFreak reports. Youtube-mp3.org also claims that its servers have been blocked by YouTube, preventing any more conversions. (At the time of this writing, however, the site's MP3 extraction tool worked for me.)

Over the years, YouTube has struck deals with record labels such as Warner Music Group and Universal to host music videos on the site. Although the music is always free, most videos have links to buy the songs on iTunes, Google Play and AmazonMP3. The video is supposed to be promotional, but conversion sites provide a way to take the music with you at no charge -- a practice that surely riles copyright holders.

In an open letter, “Philip” from Youtube-mp3.org argues that Google, which owns YouTube, is being hypocritical, noting that the company scanned out-of-print books into digital form without permission, and shows news snippets from online publications on Google News at no cost, even as some publishers demand payment. Likewise, Philip argues that his site is bending the rules to serve the needs of users.

But aside from that emotional appeal, websites that provide Youtube-to-MP3 conversion don't have a strong argument to stand on. YouTube's API terms of service forbid users from extracting individual elements from a video -- such as the audio component -- and from making any part of the video available for download. Conversion sites clearly violate those terms or service.

It's not clear why YouTube is taking action now, since these sites have been around for a while. My guess is that copyright holders are pushing YouTube to crack down as the site tries to secure more professional content. Even if YouTube swats down some sites, others will surely crop up, and standalone conversion tools will remain available. But for those rights holders, at least it looks like Google's doing something.

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