There are still a lot of people that want to enable iframes in the TinyMCE Editor within Joomla. I often will embed YouTube videos in my Joomla articles to add substance, better illustration and examples. By default, TinyMCE will strip out the iFrame tag.
This step-by-step guide shows you how to quickly enable iframes in the TinyMCE editor
Login to your Joomla Administration and go to Extensions > Plugins (Indicated by the Green Arrow)
In the filter field, type the word "MCE" (without the quotes). and click the filter button. (Indicated by the Red Box)
You will now see the Editor - TinyMCE plugin. Click on it. (Indicated by the Orange Arrow)
There are a lot of setting within the plugin configuration but if you scoll down, you will find a field called Prohibited Elements, and within the field, you will see "script,applet,iframe" already prefilled.
All you have to do is remove the word "iframe" and the comma that preceeds it and click the save & close button.
Now, in your Joomla Article, just click on the Tools menu on the far right to bring out the source code window, and paste your Youtube or other iframe code as shown below:
You will now see the video show up in your Joomla Article:
Just save the article and you're done. The video will show up in your Joomla Article for people to view!
As you can see, the TinyMCE editor will not strip the iframe code when saving Joomla articles now.