By default, Joomla automatically strips out iframe and some other HTML elements for security reasons. In order to embed videos from popular providers like YouTube and Vimeo, you have to disable the filtering of the iframe tag. This tutorial will cover how to do it for the default Joomla! TinyMCE editor.
Step 1: Editing TinyMCE Setting.
Login as admin, chose Extensions-> Plugins-> Editor - TinyMCE-> Prohibited Elements, delele ,iframe
Step 2: Chose a video.
If you want embed a video in youtube.com, open video you want, click to button Share, then chose tab Embed and copy code
If you want embed a video in vimeo.com, open video you want, click to button Share, a new window open, copy code below Embed
Step 3: Embed video to joomla article.
Login to your joomla admin site, create or open article you want embed video, in editor, click to Toogle editor, paste code you have just copy above to editor
In front-end, you will see video embedded in your article: