Yes. After end users have signed up for their own accounts, you can pay for their subscription(s) even while they control access to the content in their accounts.
Just add the email address associated with the end user's account to the URL of the account page. For example, if your domain powered by Camio is video.acme.com, then the account page URL looks like this:
You'll see this message at the top of the page as confirmation that your payment is being applied to the desired end user:
NOTE: When you're paying for > 25 Subscriptions, you MUST NOT delete your Stripe Customer object until you've cancelled all your Subscriptions. Due to a limitation in Stripe, deleting a Customer object with more than 25 subscriptions might timeout and leave the existing Subscriptions unable to be cancelled. Please contact us prior to deleting any Customer paying for more than 25 subscriptions.