Add support for video visibilty

[offish]

Currently, every video uploaded is set to public.

[yashmangal1203]

I had this problem, but was quite easy to fix.
All you had to do is create a new Constant same as in the constants.py :
"PUBLIC_BUTTON" = "PUBLIC"
"PRIVATE_BUTTON" = "PRIVATE"

Then change the upload.py as following:
in the 166th line it reads public_main_button = modal.find_element_by_name(PUBLIC_BUTTTON)
Change it to public_main_button = modal.find_element_by_name(PRIVATE_BUTTON)

This will default it to Private.