Player strings override

In this demo, player strings are being overridden by Flashvars using the "strings" plugin.
To override a string, define a new value for its key.
For the following player, the keys and values are specified:

• "mwe-embedplayer-play_clip": "Click to play"
• "mwe-embedplayer-pause_clip": "Click to pause"
• "mwe-embedplayer-player_fullscreen": "Enter full screen"
• "mwe-embedplayer-volume-mute": "Turn sound off"
• "mwe-embedplayer-volume-unmute": "Turn sound on"