Actually I would like to thank you for pointing out, I haven't thought of going further but there are a lot more feature we can try out with this 'very serious, lightweight, dependency-free Python library' mentioned here (pypi.org/project/pytube).
Well for someone who is starting with Django, Python, pytube, this may be an interesting and a fun beginner project if not there's a next step too. If you say 'how to download youtube videos?', we may get many options to choose from the websites or applications available out there but it is good if can create our own. Moreover, this library does not use any third-party dependencies and aims to be highly reliable.
I won't be able to say we can download the restricted videos as it is restricted but I'm sure some of them can't be downloaded we can check it by checking the properties of objects.
Similarly, any checks can be done by creating the objects and getting its properties.
Links:
studytonight.com/post/pytube-to-download-youtube-…
pypi.org/project/pytube