@polesye I disagree. The 'this' in 'this.onMouseEnter.bind(this)' refers to VideoCaption. So in the statement 'this.onMouseEnter.bind(this)' you bind 'onMouseEnter' to something it is already bound to. And in any case, if you look at the body of 'onMouseEnter', it uses 'this.state.config.captionsFreezeTime' which seems to indicate that we want 'this' to equal VideoCaption and not 'this.subtitlesEl'.