What Tom doesn’t mention is that Flash 9 has a a new attribute for the tag called allowNetworking. When set to “internal”, it prevents the use of any Flash Player APIs which interact with the browser, including getURL() which is used to link to other pages from the player. (Note that josh endquote explained this to me). He writes:

“MySpace now transparently adds ‘allowNetworking=”internal”‘ to all Flash Player instanced placed in its pages, effectively disabling any buttons which link anywhere.”

So stuff like Slide.com, RockYou.com, and YouTube’s Flash video wrappers will no longer be able to link back to the sites if the user is using Flash 9.

MySpace can say all they want about wanting to protect users, but really this is about them protecting their advertising dollars. The barnacle-like secondary market sites will have to find increasingly creative techniques to launch Flash-based content within the site if they want it to spread virally.

That’s a major blow against the viral spread of services like YouTube, RockYou and countless emerging others. I’ve been talking to a lot of widget vendors lately, and “it works in MySpace” is a now a primary selling point. Companies are investing large amounts of money in widgetizing content from one site onto another and MySpace is huge. This move, in the name of security, will likely do serious damage to the cottage industry of flash widgets in MySpace. In as much as users love their widgets, that means this will do serious damage to MySpace as well.