Like kj...54 said above, those are great videos composition wise and I don't think a ND filter would have made much of a difference in two of them. In the second one, perhaps it would have made the motions of the football players and the ball a little smoother. The first and third are a little over exposed in my opinion; and more so when the camera faces the sun in the first one - but that is always a hard one to get right. What I also see in all three videos is a very flat colour profile and you can certainly improve that in post. But before worrying about that, learn to get your exposure right. Always keep an eye on the histogram and the ev value and adjust the shutter speed as needed so that the ev value is between -0.3 and +0.3 and the histogram peaks at the centere. There is a lot of great posts in this forum on this matter so look around, you will learn a great deal. Here is one post I found very helpful when I was also starting out not that long ago.
If I am up in the air and my EV is far away from 0, do I change my shutter? If I am filming 30 fps I keep it on 1/60, but of course sometimes I fly up and realize I have the wrong filter on. How far can I change my shutter to get this EV I desire and at what EV value should I consider changing...
mavicpilots.com
Bottom line, you don't need a ND filter to get your exposure right.