How to add an oembed provider

I am trying to set up a site where we have to provide a very large archive of video, so I developed a very light oembed provider.

I’ve been trying to integrate this with WordPress by adding the provider in a plugin. The provider integrated nicely with Drupal, but fails with Error #1085 (which I think may be a Jplayer error rather then wordpress). An example link is of the form “https://ei.louissimons.com/videos/3%20wanderings” and the oembed url would be “https://ei.louissimons.com/oembed?url=http%3A%2F%2Fei.louissimons.com%2Fvideos%2F3%2520wanderings”.

Should it be as simple as making the following plugin (which currently fails)?

<?php
/*
<plugin descriptive info>
*/
wp_oembed_add_provider('https://ei.louissimons.com/videos/*', 'https://ei.louissimons.com/oembed');
?>

Is there a way to print the list of registered providers or a tactic to debug why the oembed is failing?

Thanks,
Louis