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Opera really need to sort out their support for plugins apart from flash working ok'ish almost every other plugin is broken or not supported.
e.g. quicktime, java, javafx, unity, silverlight, etc.
I hope they fix this situation soon.
Opera's support for plugin's isnt' that bad. flash has been problematic recently (shockwave specifically) but Unity (I assume you mean http://unity3d.com/webplayer/ ) and many others (quick time also isnt perfect, but its not great on the windows playform either).