Applies a partial update to a video's related-media customizations. Only the
fields supplied are changed; sending a field as null deletes it (reverting to
the default).

Requires api token with one of the following permissions

Read, update & delete anything

Tokens with the "Act with a team member's permissions" permission
(all:delegate_to_contact_permissions scope) can also be used. Requests
made with such a token are authorized using the permissions of the
contact assigned to the token.

An expiring access token
created with the all:delegate_to_contact_permissions scope and an
authorization granting the edit permission on this media can also be used.