install libraries given in "requitrements.txt"
there is an issue with stream function in pytube go to pytube/cipher.py
look for :
r'a.[a-zA-Z]\s*&&\s*([a-z]\s*=\sa.get("n"))\s&&.?||\s([a-z]+)', r'([a-z]\s*=\s*([a-zA-Z0-9$]+)([\d+])?([a-z])',
replace it with:
r'a.[a-zA-Z]\s*&&\s*([a-z]\s*=\sa.get("n"))\s&&.?||\s([a-z]+)', r'([a-z]\s*=\s*([a-zA-Z0-9$]+)([\d+])([a-z])',
your code will download the link