not bad
I only watched your first two vids, but I gotta say other than some errors, your doc isnt lookin bad.
Biggest problems I saw:
1) Be careful with how much you dodge roll. The more experienced opponents you play, the more punishment you'll recieve. I can see you know wavedashing, so start trying to incorperate it into your main game.
2) The f-air is a great move, but don't over use it. In the first vid, you had many great oppurtunities to use n-air/u-air but instead went with the f-air. In the second vid you seemed to use your other air attacks more which, even though they had no chance of getting a kill, set you up to get more attacks in, raising that percentage up, and finally getting that ever-so-satisfying kill.
3) You should probably do more short hop pills than full jump pills. First off, short hop pills stay closer to the ground, disrupting someone who is trying to rush to get to you. Second, Full jump pills leave you semi-vulnerable in the air, plus they tend to bounce over an opponent's head.
4) On recovery, work on sweetspotting that ledge. Even the slightest part of your head coming over the edge will give any player (especially a Marth) a great oppurtunity to deal serious damage. Remember, Doc seems to have magnetic hands, so even though it looks like you shouldn't grab the edge, you might be able to pull it off. Just practice it for a while until you find the right distance.
In all honesty, your Doc can hold his own against some above average competitors. The four ideas I brought up are all just the teensy tiny little minute details that make a huge difference in between a good player and a pro.