import re
rx = r"//([^/]*\.[^/:]+)"
strs = ["http://f...content-available-to-author-only...o.com/", "http://x...content-available-to-author-only...b.we--p1qw/vse_seeei_podryad/mqwetiki",
	"http://w...content-available-to-author-only...e.com/ru/", "http://e...content-available-to-author-only...y.to/%D0%qwewqeD0%BA%D1%83%D0%BD%D0%B8%D0%BD",
	"http://name@while.com", "http://n...content-available-to-author-only...x.into/v-vashem-aktive-net-inostrannyx-yazykov-ne-kruchintes",
	"http://f...content-available-to-author-only...t.com:80/books/90359"]
for s in strs:
	m = re.search(rx, s)
	if m:
		print(m.group(1))

aW1wb3J0IHJlCnJ4ID0gciIvLyhbXi9dKlwuW14vOl0rKSIKc3RycyA9IFsiaHR0cDovL2YuLi5jb250ZW50LWF2YWlsYWJsZS10by1hdXRob3Itb25seS4uLm8uY29tLyIsICJodHRwOi8veC4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4uYi53ZS0tcDFxdy92c2Vfc2VlZWlfcG9kcnlhZC9tcXdldGlraSIsCgkiaHR0cDovL3cuLi5jb250ZW50LWF2YWlsYWJsZS10by1hdXRob3Itb25seS4uLmUuY29tL3J1LyIsICJodHRwOi8vZS4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4ueS50by8lRDAlcXdld3FlRDAlQkElRDElODMlRDAlQkQlRDAlQjglRDAlQkQiLAoJImh0dHA6Ly9uYW1lQHdoaWxlLmNvbSIsICJodHRwOi8vbi4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4ueC5pbnRvL3YtdmFzaGVtLWFrdGl2ZS1uZXQtaW5vc3RyYW5ueXgteWF6eWtvdi1uZS1rcnVjaGludGVzIiwKCSJodHRwOi8vZi4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4udC5jb206ODAvYm9va3MvOTAzNTkiXQpmb3IgcyBpbiBzdHJzOgoJbSA9IHJlLnNlYXJjaChyeCwgcykKCWlmIG06CgkJcHJpbnQobS5ncm91cCgxKSk=