The RTE in Umbraco 7 (and since v4.9) offers a super simple way of inserting rich content from third party services (videos from youtube, image from flickr, …) but sometimes your editors will try to insert something that isn’t supported…
Luckily you can easily plug in additional third party services
If service support oembed
In that case it should just be a matter of adding an additinal entry to the EmbeddedMedia.config file. Let’s say you want to support videos from TED.
The details we get from oembed:
URL scheme: http://ted.com/talks/*
Example: http://www.ted.com/talks/oembed.xml?url=http://www.ted.com/talks/jill_bolte_taylor_s_powerful_stroke_of_insight.html
So with those details I can add a new entry to the config file (just look at the existing ones to get an overview of the xml elements you need).
And now content editors can easily insert talks from ted.com
If service doesn’t support oembed
Even if the third party service doesn’t offer oembed support it’s still possible to provide this easy way of inserting rich content.
Since you can write custom providers, so if the service has an API you can take advantage of that.
Here is an example of a custom provider, this one adds Giphy support.
So once this provider is in place we also need to add an entry to the config file
And now our content editors can insert gifs 
So that’s how you can use the EmbeddedMedia.config file, sourcecode for the example provider is available on github https://github.com/TimGeyssens/UmbracoExampleEmbedProvider