YouTube explicates the Friday phenomena in a blog post today, demonstrating how searches for "Rebecca Black" have remained strong on the video-sharing site following the video's viral kick-in-the-you-know-what. For comparison's sake, other searches for viral videos (such as "Golden-Voiced" homeless man) have waned during the same time period after release.
The most interesting observation, however, is the obvious: Searches for "Rebecca Black" spike every Friday. YouTube also says that searches for "Friday" have also spiked; the site is seeing more searches than ever for this term.
Granted, the video hasn't been out for too long, and it did get considerable buzz last Friday when Rebecca Black took over Funny Or Die, but the observation is interesting all the same.