I think you are over estimating the standard of proof required. This is not
like a criminal case where one must prove beyond a reasonable doubt. It is
more like a civil case - - more likely than not. Email yourself a
screenshot of the title slide with an attestation that "I watched this" and
you will pass an audit every time.

As a "Cio" you might think more holistically. At my organization a dozen of
us schedule a webinar and then hang around discussing it and other common
things. We then go off and file CPEs for our various certs and I send a for
the the record email to the attendees.

For webinars the description is optional. It was added (I suspect) because
a bunch of us wanted to put a link to webinar for our own benefit.