Content on sites such asandis user-generated, which has given a whole new dimension to the viral sharing of music videos across the web. Such websites allow music videos to be distributed without any approval from the recording companies.This has caught the attention of the, and in recent weeks, it has been stepping up its efforts to stop sharing of popular videos on YouTube. The site, which boasts over 6 million visitors and 40 million streams per day, has become a harbor for unlicensed music videos, much of which is coming frombroadcasts which are recorded by users withand other digital video recorders and posted onto the site.The RIAA recently dealt cease-and-desist letters to some YouTube users caught sharing unlicensed music videos of popular artists. Links to videos taken down by the RIAA now give the greeting,The major labels believe that it's the responsibility of such sites to monitor the content passing through their own communities. But so far, they have been targeting only individuals who use these sites to share popular music videos. The problem with this seems to be that many of the videos that the major labels have requested be removed have quickly reappeared on the site within days, and industry sources believe this supports the requirement for stricter filtering by all viral video specialists.Both the RIAA and YouTube have declined to comment.