$ python3
Python 3.9.2 (default, Feb 28 2021, 17:03:44)
[GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pytube import YouTube
>>> yt = YouTube('https://www.youtube.com/watch?v=bmXP-58FItA')
>>> yt.streams.filter(type='video').get_highest_resolution().resolution[0:-1]
'720'
>>>