If your browser does not already have a WMP plugin then that is why the radio web site won't play.
I suspect that what they mean is, you need 'at least' a version 11 plugin.
This does not affect your Windows 7 system WMP at all.
Mark
My computer has Windows 7 with Windows Media Player 12. When I go to a certain internet radio web site and want to 'listen live', I get a message that I need to install Windows Media Player 11 plug-in. Since I have a later version of WMP, why do I need the earlier?

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