<iframethe literal text <iframe (case insensitive) \sany whitespace character
Group 1((?!src)[^=]*="[^"]*"\s){0,3} {0,3}repeats the group contents below between 0 and 3 times:
Negative Lookahead(?!src) srcthe literal text src (case insensitive) Negated Character Class[^=]* *matches any number of characters outside the set below:
=the literal = (6110 / 758 / 3D16)
Negated Character Class[^"]* *matches any number of characters outside the set below:
"the literal " (3410 / 428 / 2216)
"the literal " (3410 / 428 / 2216)
\sany whitespace character
src="the literal text src=" (case insensitive) Non-Capturing Group(?:https|http) httpsthe literal text https (case insensitive) httpthe literal text http (case insensitive) :the literal : (5810 / 728 / 3A16)
\/the literal / (4710 / 578 / 2F16)
\/the literal / (4710 / 578 / 2F16)
Negative Lookahead(?!www.youtube.com\/|youtube.com\/|player.vimeo.com\/) 1st Alternativewww.youtube.com\/ wwwthe literal text www (case insensitive) .any character
youtubethe literal text youtube (case insensitive) .any character
comthe literal text com (case insensitive) \/the literal / (4710 / 578 / 2F16)
2nd Alternativeyoutube.com\/ youtubethe literal text youtube (case insensitive) .any character
comthe literal text com (case insensitive) \/the literal / (4710 / 578 / 2F16)
3rd Alternativeplayer.vimeo.com\/ playerthe literal text player (case insensitive) .any character
vimeothe literal text vimeo (case insensitive) .any character
comthe literal text com (case insensitive) \/the literal / (4710 / 578 / 2F16)
Negated Character Class[^"]* *matches any number of characters outside the set below:
"the literal " (3410 / 428 / 2216)
"the literal " (3410 / 428 / 2216)
Negated Character Class[^>]* *matches any number of characters outside the set below:
>the literal > (6210 / 768 / 3E16)
>the literal > (6210 / 768 / 3E16)
.*?any character, repeated any number of times
<the literal < (6010 / 748 / 3C16)
\/the literal / (4710 / 578 / 2F16)
iframe>the literal text iframe> (case insensitive)