Remove broken link from docs

Closes gh-8986

Author: eleftherias

docs/manual/src/docs/asciidoc/_includes/about/exploits/headers.adoc

@@ -174,7 +174,7 @@ Refer to the relevant sections to see how to customize the defaults for both <<s
 ====
 
 Allowing your website to be added to a frame can be a security issue.
-For example, using clever CSS styling users could be tricked into clicking on something that they were not intending (https://www.youtube.com/watch?v=3mk0RySeNsU[video demo]).
+For example, using clever CSS styling users could be tricked into clicking on something that they were not intending.
 For example, a user that is logged into their bank might click a button that grants access to other users.
 This sort of attack is known as https://en.wikipedia.org/wiki/Clickjacking[Clickjacking].