#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)(?<=src=").*?(?=[\?"])"
Local $sString = "<iframe src="http://www.youtube.com/embed/NM51qOpwcIM?modestbranding=1;rel=0;showinfo=0;autoplay=0;autohide=1;yt:stretch=16:9;wmode=transparent;?wmode=transparent" allowfullscreen="" style="width: 640px; height: 361.057px;" frameborder="0"></iframe>" & @CRLF & _
"" & @CRLF & _
"<iframe src="https://www.youtube.com/embed/VASywEuqFd8?feature=oembed" allowfullscreen="" width="660" height="371" frameborder="0"></iframe>" & @CRLF & _
""
Local $aArray = StringRegExp($sString, $sRegex, $STR_REGEXPARRAYGLOBALFULLMATCH)
Local $aFullArray[0]
For $i = 0 To UBound($aArray) -1
_ArrayConcatenate($aFullArray, $aArray[$i])
Next
$aArray = $aFullArray
; Present the entire match result
_ArrayDisplay($aArray, "Result")
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