comment on

$_ =~ /(http:\/\/[\w\.]+)/g;

seems to work OK for URLs starting http://, but that doesn't match www.mysite2.com as that doesn't have a http prefix in your example string.

VGhpcyBtZXNzYWdlIGludGVudGlvbmFsbHkgcG9pbnRsZXNz

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