I know that WP_oEmbed is a class used by WordPress to handle oEmbeds. Is this available as a global or should I create a new instance of it?

Update: I have found a function called _wp_oembed_get_object() which says in the documentation:

This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.

Update 2: FYI, I plan on calling a number of its methods for something I am working on.

Update 3: For now, at least, I'm assuming $oembed = new WP_oEmbed(); is the best practice.