In the screen capture video part the EV was set to -3. If it was a low light time of day -3 is to low of a setting. Probaby +3 would have put you in the ballpark. I sometimes run into this going out into the sun and when I turn around and start coming back everything goes dark. Use the EV wheel to adjust it.
It wasn't a low light time of day. It was about 2:30pm, and very bright and sunny. All of my vids have been comming back very dark unless I point the camera down.
How do they look to you on your phone\tablet screen? To me in your screen capture video it was way to dark and needed some adjustment in the EV settings.
Yep, even in AUTO the exposure wheel can change settings. Accidentally hit mine while flying and went the other way - overexposing a few seconds of video before looking at screen and seeing all white! Fat fingers and not paying attention...