#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(<a\s+[^>]*?href="[^"]*#!(\[.*?\])"[^>]*?>[^<>]*?<span[^>]*?>[^<>]*?<\/span>[^<>]*?<\/a>)"
Local $sString = "<a href="https://mega.co.nz/#![RandomThings1]" target="_blank">[RandomThings2] [<span style="color:#008000;">[RandomThings3]</span>]</a>" & @CRLF & _
"" & @CRLF & _
"needed:" & @CRLF & _
"<a href="https://mega.co.nz/#![RandomThings1]" target="_blank">[RandomThings2] [<span style="color:#008000;">[RandomThings3]</span>]</a> <a href="http://no.refer.co/?link=https://mega.co.nz/%23![RandomThings1]" target="_blank">NoRefer</a>"
Local $sSubst = "$1 <a href="http://no.refer.co/?link=https://mega.co.nz/%23!$2" target="_blank">NoRefer</a>"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm