Unfortunately the plugin for Firefox will not work in Opera - but at least you'd know if Flash is still supporting XP or you need to find an older version.
Let's get a thread of its own, or move ourselves to that one of mine, but the thing is my Opera 36 installation has not ever had any trouble at all with any plug-in Flash included. Moreover, it got me an impression it somehow connects with - all that.
I mean Opera never asking for anything, just working, then Firefox time to time - updating stuff -- etc. Working.
Maybe I'm blessed
That's great, but telling me yours has never had problems, doesn't exactly help me now does it?