There is no point in storing a video with an empty src value. According to Checklist If you use a video tag, you must set a correct src attribute, but you didn't set any. Furthermore it's possible to convert this media to a correct iframe — check the Brightcove documentation https://support.brightcove.com/choosing-correct-embed-code#iframe. See also Checklist, p. 6.4.2:
"1. If the unsupported widget has an iFrame version, make it into an <iframe>.
2. If it is not possible to represent the widget as an iFrame, but it is possible to get a direct link to the video/audio, use this link to generate a <video> or <audio> with the correct src attribute.
3. Otherwise, mark the object with the @unsupported function."
Other example-links:
https://www.yorkshireeveningpost.co.uk/sport/football/leeds-united/gary-mcallister-lost-teeth-in-unprovoked-knuckle-duster-attack-reveals-former-leeds-united-star-dominic-matteo-1-9671288
https://www.yorkshireeveningpost.co.uk/news/traffic-and-travel/flybe-cancels-flights-across-the-u