Currently, Shumway is enabled only for product tour videos on Amazon, only on Windows and OS X, and only in the Nightly version of Firefox, according to Mozilla programmer Chris peterson. But the Shumway team has been improving compatibility with Flash video players and will whitelist more Flash video sites soon, he added. Shumway needs H.264 video decoders that may not be available on Windows XP or Linux.
Flash plugins expand what Web browsers can do, but they also open up new security holes and crash problems. They also require large amount of processing resources to run.