Hey conti! You're in luck-I'm taking a break from a paper here at 3:15 in the morning and I'm in the mood to critique! I only watched the first video.
Here's what I got:
-You roll a lot-it isn't all bad, but I do think it is particularly bad against marth. While this marth wasn't doing it a lot, marth is particularly good at punishing rolls. When playing experienced marths I've found that marth doesn't even really have to predict the roll-he can simply react with dancing blade :O. Also, be careful about always rolling after being tripped. Remember you have four options when tripped, not merely two.
-After a grab, pummel. Refreshes your moves, etc. It's tough to get into the habit of, I know.
-We all have our own styles, and your seems particularly aggressive. I am naturally the other way, so maybe its just me saying this but I think you need to camp a bit more vs marth. If we play offensive vs marth, we make his life much easier. I saw next to no peanuts shot by you all game, and I do believe that the peanut popgun may be our greatest weapon against marth. My strategy against marth is to set up ADHD's 'wall' as much as possible. So what I'm saying is that I recognize you're a naturally aggressive player, I do believe it necessary to camp against marth from time to time.
-I've noticed you've picked up ADHD's fairly recent method of pulling banana's-and who hasn't! His run offstage, full hop, pluck pluck, jump, instant throw is a great way to set up combos and even banana locks. However, I've found this to be generally unsafe if done too much, and in the video I watched you seemed to be going out of your way to do this. Doing this too much, particularly against characters like marth and meta knight will get you gimped, so I'd try to limit doing that to once or twice a match rather than the 6 or 7 times you attempted it.
-Grab nanas off platforms with aerials if you're going to go for them and marth is right there. A few times I thought you could've done that instead of z grab.
Great use of uthrow. I love that throw in this matchup. Marth is seemingly helpless when above us, and uthrow is an amazing tool in this matchup.
Neat mixups with your recovery! you did a great job of not only recovering from a far with peanuts etc, but gettting off ledge against marth, who is probably the toughest character for diddy to get off the ledge against! Great job!
Sorry for this long winded critique. You should give yourself more credit! You have a good diddy. You use safe, smart options in almost every situation and you tend to read your opponent fairly well. I hope this critique can be of help. I hope it didn't seem harsh either, I do think you're very good. Everybody has lots to work on, even my good friend Wyatt would admit this I believe.