XF 2.3 How do I use iframe to display embedded links from my video streaming site?

[zoldos]

I have a small Youtube "clone" streaming site. It can produce embed links for videos such as below:

<iframe src="https://xxxx.com/embed/RvtVstTMzeoCsga?color=04abf2" frameborder="0" width="700" height="400" allowfullscreen></iframe>

However, this doesn't work on my forum. It just shows the link. I've enabled "Convert Markdown-style content to BB code" and I added "iframe" to "Allowed code BB code block languages". But honestly, I have no idea what I'm doing.

Can anyone assist? Thanks!

@JoshyPHP