import re
strs = ['http://w...content-available-to-author-only...s.com/','http://w...content-available-to-author-only...s.com','https://w...content-available-to-author-only...s.com/','https://w...content-available-to-author-only...s.com']
r = re.compile(r'https?://([^/]*)/?')
for s in strs:
m = r.search('http://w...content-available-to-author-only...s.com')
if m:
print(m.group(1))
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