For simple code, may be i think
import os
os.system('youtube-dl [OPTIONS] URL [URL...]')
Above is just running command line inside python.
Other is mentioned in the documentation Using youtube-dl on python Here is the way
from __future__ import unicode_literals
import youtube_dl
ydl_opts = {}
with youtube_dl.YoutubeDL(ydl_opts) as ydl:
ydl.download(['https://www.youtube.com/watch?v=BaW_jenozKc'])