Win 8.1 x64, Opera 32.0.1948.19 -- All three videos are OK
I actually saw this message (Ez a böngésző nem támogatja a videólejátszást) for a tick on a second video while activating the plugin (I have them off by default), maybe there's a problem with this local flash video player this site uses?
This settings may help (untested!):
Perhaps its a problem with hardware acceleration of graphic card in Opera 24.