Sales of Blu-ray Disc titles are still so relatively small compared with standard DVD that only one or two new disc releases in any given week can directly affect Blu-ray's overall share of the video-disc pie. And because of the prevalence of Blu-ray Disc players in all PlayStation 3 video game consoles, Blu-ray titles tend to skew to the youngest age demographics.

Thus, the recent Blu-ray release of several titles that enjoy younger audiences likely is most responsible for growing Blu-ray's revenue share to 13 percent, (a week earlier, it was 8 percent).

For the week ending Feb. 28, Blu-ray sales totaled $21 million — up nearly 77 percent over late-February 2009. Standard DVD's share of 87 percent resulted in sales of nearly $137.5 million (down more than 26 percent from a year ago).

But overall video-disc sales of both formats were down more than 20 percent over the same week a year ago, according to Home Media Research.