The Flash plug-in for Opera in Kubuntu has been FUBAR-ed and it seems that it's caused due to an Opera bug w.r.t Flash player 9.0.115 which is fixed in the 9.50 betas. However, since Kubuntu etc. are still using 9.27, the only way to fix this issue is to go back to 9.0.48.
To do this, download the Flash 9 player archive and extract and copy the 9.0.48 libflashplayer.so to the Opera plug-ins directory -
/usr/lib/opera/plugins. Now, restart Opera and navigate to the download preferences page via Tools, Preferences, Advanced and Downloads. Select
application/x-shockwave-flash | swf and click edit. In the "Use plug-in" section, select the plug-in from /usr/lib/opera/plugins. Click OK and restart and voila etc. etc.
If you want to be cute, you could also do the above for