You cannot override the * button when using the roVideoScreen. You could implement your own custom player using roVideoPlayer and roImageCanvas or roScreen, which would allow you to assign custom functionality to the * button, but would also require you to custom code everything else, including the UI and trick play functionality.
A better option, if you don't have control over the CC implementation, may be to add the language selection to the springboard screen instead, so the user chooses it prior to launching playback.
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