I embed a lot of media in Content pages from YouTube to PowerPoint to an assortment of Web 2 tools (Web 2.0 Tools)
A quick an easy tip to make them flow with other text is to add in a border with a slight gap. I use the following HTML
style="padding: 1px; border: 1px solid black;"
I add this feature just after the first iframe tag eg
<p><iframe style="padding: 1px; border: 1px solid black;" src="https://onedrive.live.com/emb..........
What this does is add in a border around the iframe which makes it look a little more presentatable eg
BEFORE ADDING BORDER
AFTER ADDING BORDER
The border comes into play when there is little colour to define the edges