Some nice scenes there. I'm self-taught and have much to learn, but here are my pointers:
1. The biggest improvement to your video will come from editing-out sharp course corrections and camera tilts. In-film camera movement needs to be slow. You can change your controller input settings or fly in Portrait-mode to help avoid twitchy movement. Avoid Sports-mode.
2. I'm a sucker for horizontal pans. They're a tempting way to capture a vista, but use them sparingly. The compression on YouTube (low bit-rates) will leave you with a smear of pixels. As per above, slow it down.
3. Fancy transitions tend to detract from your subject matter. I'll either use no transition, fade-out / fade-in or sometimes a merge if I want to show continuity.
4. Vary your footage by bringing your subject matter closer (you do have a few closer shots), shooting straight down, or using 'reveal' techniques such as pull-backs or slow upward pans. Proximity flying is fun for the pilot and provides more interesting footage - but you risk hitting something.
5. Shooting into the sun can get you some nice effects (particularly with autumn leaves), but generally speaking, keep the sun behind you. And of course, early morning or late evening light can transform your footage.
6. Auto-exposure works for me. I use it because it suits the way I fly - basically, picking angles as I go. I don't want to have to set up each shot. However, you need to be alert to exposure problems. The greater the range of bright and dark in your scene, the more likely your camera won't be correctly exposing what you want it to. Irrespective of whether you're flying auto or manual, a bright sky combined with ground in shadow (as you had in a handful of scenes) should be avoided, as your camera will struggle to correctly expose either the sky or the land. If you need that shot, tilt your camera down to remove the bright sky and your exposure will correct.
Happy flying!