This is an H2.
This is an H3.
This is an H4.
And of course body text.
The old way of embedding video:
The better way…wrap it in a Section, or in Columns. Those wrapping containers will make sure they display and resize correctly. And DON’T USE AN IFRAME! Use an Embed. In this example, it’s the Youtube Embed. Lastly, just be sure to Align Center both the video and its container.