Can I use Shockwave inside WebXtra?

Unfortunately, no. At this time, the Shockwave plugin will not initialize correctly when it is hosted on another instance of the Director player. This is also true if you try to use for example Macromedia's own ActiveX Xtra to host Shockwave. Trying to host Shockwave content inside WebXtra may generate a fatal error in Director, or a crash. This issue has been reported to Macromedia and is currently under investigation.

YES! This issue has been fixed by Adobe and WebXtra 5 running in Director 11 can now properly host Shockwave movies.