this.playhead.nativeElement.addEventListener('mousedown', this.mouseDownEvent.bind(this));
window.addEventListener('mouseup', this.mouseUpEvent.bind(this));

mouseDownEvent(ev: any) {
    this.mouseDownOnPlayhead = true;
    this.pause();
    window.addEventListener('mousemove', this.manuallyMovePlayhead.bind(this), true);
}

mouseUpEvent(ev: any) {
    window.removeEventListener('mousemove', this.manuallyMovePlayhead.bind(this), true);
    this.mouseDownOnPlayhead = false;
}

manuallyMovePlayhead() {
    ... // Do Stuff
}