func fetchVideoURL() {
        Database.database().reference().child("programs").child(refWorkout).child("exercises").child("videoURL").observeSingleEvent(of: .value) { (snapshot) in
            self.url = snapshot.value as! String

        }

        let newURL = URL(string: url)
        let player = AVPlayer(url: newURL!)
        vc.player = player
        present(vc, animated: true) {
            self.vc.player?.play()
        }
    }