Several years ago, WordPress.com introduced oEmbed provider support to allow posts on WordPress.com-hosted blogs to be embedded anywhere that supported oEmbed. WordPress 4.4, due out in December, will bring oEmbed provider support to the wider WordPress world.
One week from today, on October 2, the WordPress.com team will be switching our oEmbed format to match the global WordPress format. The oEmbed spec allows for arbitrary changes in the HTML being returned, but since this is a significant change we wanted to give everyone ample lead time.
We understand that not everyone is comfortable with embedding arbitrary scripts on their page. If you wish, you may strip the script tag and provide the same functionality using the script from the development plugin. If you choose this method, please keep in mind that this script is still under development, and will likely change between now and WordPress 4.4’s release.
In order to test the new embeds, simply add the query string ?newembed=true to the URL of any post hosted on WordPress.com, like so. Similarly, you can get the output from our oEmbed endpoint by adding &newembed=true to the end of the request. We’re still working on adding support for this new style of embed to the WordPress.com post editor, but you can test it on your own WordPress install using the feature plugin.
If you run into any issues or have any questions, please post them in the comments below!
Update: September 25, 2015 16:00 UTC — We are temporarily reverting this change. Please see the comment below. We’ll update this post when the new oEmbed is re-enabled.