adds custom domains video

Author: ZPain8464

content/docs/capabilities/custom-domains.mdx

@@ -8,6 +8,16 @@ description: The Custom Domains page teaches you how to add your own domain in P
 
 # Custom Domains in Pomerium Zero
 
+<iframe
+  width="100%"
+  height="500"
+  src="https://www.youtube.com/embed/qj1D5Rgziz0?si=hXM8itfRJ_2lXztP"
+  title="YouTube video player"
+  frameborder="0"
+  allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
+  referrerpolicy="strict-origin-when-cross-origin"
+  allowfullscreen></iframe>
+
 This document describes **Custom Domains** in Pomerium Zero.
 
 ## Overview