I was trying to make a YouTube mp3-mp4 downloader to practice python. But I'm getting this error always. I tried something but nothing was helpful. I tried using "global YouTube" but I don't know what is the true usage. I downloaded pytube before downloading pytubex I wonder if it affects the code. I checked other peoples codes and I couldn't see the difference.
from pytube import *
from distutils import command, extension
from tkinter import *
from tkinter import filedialog
app = Tk()
app.title("Youtube MP3-MP4 Downloader")
app.geometry("350x450")
def mp4Button():
    directory1= filedialog.askdirectory()
    url= urlEntry.get()
    yt= YouTube(url)
    video = yt.streams.first()
    video.download(directory1)  
def youtube1():
    button.destroy()
    urlEntry.get()
    url = urlEntry.get()
    mp4= Button(app,text="mp4",command=mp4Button)
    mp4.pack()
    mp4.place(x=100,y=75)
    mp3= Button(app,text="mp3")
    mp3.pack()
    mp3.place(x=100,y=100)
    
button = Button(app,text="Search",justify="center",command=youtube1)
button.pack()
button.place(x=100,y=75)
urlEntry= Entry(app,text="Enter video url",justify="center")
urlEntry.pack(fill=BOTH,ipady=10,padx=18,pady=5)
urlEntry.focus()
pathlabel = Label(app)
pathlabel.pack()
app.mainloop()
Output:
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\tkinter\__init__.py", line 1884, in __call__
    return self.func(*args)
  File "c:\pythonP\youtube mp4 mp3\pytube.py", line 12, in mp4Button
    yt= YouTube(url)
NameError: name 'YouTube' is not defined
How can I fix that I can't understand what is wrong
Thanks in advance
new error
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\tkinter\__init__.py", line 1884, in __call__
    return self.func(*args)
  File "c:\pythonP\youtube mp4 mp3\ytdownloader1.py", line 12, in mp4Button
    yt= YouTube(url)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\pytube\__main__.py", line 91, in __init__        
    self.prefetch()
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\pytube\__main__.py", line 181, in prefetch       
    self.vid_info_raw = request.get(self.vid_info_url)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\pytube\request.py", line 36, in get
    return _execute_request(url).read().decode("utf-8")
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\pytube\request.py", line 24, in _execute_request 
    return urlopen(request)  # nosec
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 214, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 523, in open
    response = meth(req, response)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 632, in http_response
    response = self.parent.error(
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 555, in error
    result = self._call_chain(*args)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 494, in _call_chain
    result = func(*args)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 747, in http_error_302
    return self.parent.open(new, timeout=req.timeout)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 523, in open
    response = meth(req, response)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 632, in http_response
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 561, in error
    return self._call_chain(*args)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 494, in _call_chain
    result = func(*args)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\urllib\request.py", line 641, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 410: Gone