Using Cloudflare Stream for wordpress website header video Is this possible?

From within the admin panel in wordpress I choose Appearance → Customize → Header Media → the Twenty Seventeen Theme allows me to choose a “Header Video”.

How can this video be utilized with Cloudflare stream?

It looks like it’s possible, but it will require creating a custom handler for Cloudflare Stream. The standard Twenty Seventeen Theme I believe only supports local and YouTube hosted videos.

There is a bit of an explanation of what needs to be done here, under Creating custom video handlers. An example custom handler for Vimeo is also provided there.

Alternatively, you could use a hook to insert a video header of your own making, in functions.php.