youtube_download.py

from pytube import YouTube
from pprint import pprint
import sys


if len(sys.argv) > 1:
    vid = sys.argv[1]
else:
    print('Usage - python3 youtube_download.py VIDEO_ID')
    sys.exit(1)

try: 
    yt = YouTube("http://www.youtube.com/watch?v={}".format(vid))
except e:
    print('Failed to get video with id', vid)
    sys.exit(1)

yt.set_filename(yt.filename + '_' + vid)

if len(yt.filter('mp4')) > 0:
    if len(yt.filter('mp4', '720p')) > 0:
        video = yt.get('mp4', '720p')
    else:
        video = yt.filter('mp4')[-1]
else:
    print('No mp4 formatted videos')
    sys.exit(1)

def on_progress(so_far, total, start):
    pass

def on_finish(filename):
    print('on_finish({})'.format(filename))

video.download('.', on_progress=on_progress, on_finish=on_finish)