This is pretty common, even in desktop media players. VLC, for example, has a play/pause button that's labelled according to action, and a mute/unmute 'button' that's labelled according to state.

I put 'button' in quotes, though, to reflect a key difference: the mute/unmute control in VLC isn't actually a button; it's an icon without button styling sitting next to the volume slider, and this appears to be the case for other desktop media players as well. Since the presentation of the control is distinct, this might be less of an inconsistency with desktop players than with these web video players.

Still, there seems to be an increasing muddle between action and state in labeling UI controls, and that's not even considering functional controls that display arbitrary information unrelated to any current state, like icons for applications that display arbitrary content from a file created or accessed by that application (I'm looking at you, Windows Phone Photo app).

I really don't understand why there's so much wild experimentation with UIs in production software these days, but I do find my count of UI-related "WTF moments" going up every month.