Bug fix for the error "this.pluginApi.pauseMedia is not a function" when using the flash player and removing the dom element.

Bug fixed: When the player's "remove" function is called it doesn't
remove the internal reference to the removed player. When the
pauseOtherPlayers option is true, the player being used is flash and the
flash dom element has been removed an error is thrown when the next
video is played.