I loaded an mp4 ad and the status comes up negative. It's definitely on, the start and end dates are correct, and I'm on the pro plan. So I don't know what the problem might be.
If you hold your mouse over the red X in the Status column, a tooltip will appear showing the reason why the ad isn't active. In your case, it's because you have the End Date on the Ad set to 2021-03-16 (yesterday). To fix, either remove the value from the End Date field or push the End Date out further into the future.