Note to self: When changing a Flash file to contain AS3 code (to be exact: setting the AllowABC flag in the FileAttributes tag), the behavior of masks changes (to be exact: the mask-and-clip test in swfdec’s testsuite creates different results). This is just to remember myself to fix this once we support Flash 9.
PS: Here’s a nice side effect of the mask stuff:
(For everyone not immediately noticing it: The Youtube intro Flash shows correctly. Yay!)