from tkinter import *
import os
import subprocess

class AppExE:
    def __init__(self, master):
        self.frame = Frame(master)
        self.b = Button(self.frame, text='Open', command=self.openFile)
        self.b.grid(row=1)
        self.frame.grid()

    def openFile(self):
        _filepath_ = ["C:\!TEST!" + chr(92) + "youtube-dl" + chr(46) + "exe ", "https://www.youtube.com/watch?v=TE3Bl2d-Mw0"]
        subprocess.run(_filepath_)

root = Tk()
app = AppExE(root)
root.mainloop()