My first language is Spanish, I'm from Canary Islands (random place in the middle of the ocean lol)
Sometimes when I double jump it's just because i feel i'm going to be punished for something I did on my first jump. So the problem, I guess, is not the second jump actually but what I did just before xD in some of the moments you pointed I double jumped I had no space and I knew that if I had landed normally any kind of aerial could have hit me. Anyway you're right, that's something I have to work on!
2:45. I roll twice, first roll I find it not punishable as he was bairing. Second roll idk. Also I think first roll was a mistake and the second one was me just trying to go back to the prior position.
2:50 airdodge was probably a platform cancel
"3:20 – consider fair to nair to fair to nair in order to extend your combo. Dair doesn’t really allow much follow ups." - This guy somehow manages to shield some of the fairs to nairs at low percentage, so I fair to dair instead. But you're correct, here a fair to nair would completely have hit xD but i better not try it at low percentage because if he blocks it it's a guaranteed nair OoS. In the rest of the set I do fair to nair, you can see that, but notice the percentage thing xD.
About the roll issue, I try to roll only when peach is in the air and performing some aerial so she can't punish (forward roll), or when she's pressuring me (backwards roll). I'll have to watch the replays again and try to improve those habits. There might be better options, you're completely right.
5:33 was a mistake as you pointed.
5:37 yep it was xD
6:23 tried to punish that smash with an uptilt, but you're completely right.
8:34 I kinda spammed fair this match for getting off the ledge. But that's one of the only options which seems to work, as the peach player always hits my normal get up, roll, jump and attack. Anyway I should try other ways of getting back to the stage.
9:35 I roll randomly sometimes and try to hit with uptilt or jab xD I did it twice in those matches i think and the first time you told me it was predictable. The second you're telling me it wasn't. I don't really spam roll so no one covers it and i don't really get punished most of the times (in this set not a single one). What i'm telling you here is that you might not have seen that coming but someone could have found that roll very predictable. IDK if we can actually say something like "man that was completely unpredictable" xD.
10:10 idk if a sideB would have hit. he rolls before i touch the ground but i wasn't even fast falling, so it could have hit. anyway i don't use it in this MU very often because peach's nair OoS destroys completely that option. And this guy moves just too much xD maybe if he kept shield for longer I would have tried it more often but it's not like hitting a snake with it. If you watch other matches of my lucario you'll see I actually use it sometimes xD. Also you will notice that I fair to dair his shield like 2 or 3 times on the whole set and it hits. That happens because he never stands on his shield and as soon as my fair hits it, he tries to punish or roll or whatever.
13:10 What I told you, I rolled when the dair hit me and punished.
13:18 completely right xD
14:28 he didn't want to do that obviously
Your conclusions-
1 Yep, should put some work into that!
2 Completely agree
3 Yeah, as I told you
4 Commented it before xD
About your spacing:
i don't think you're doing anything wrong against snake, but it's difficult to judge your spacing by just a MU where the other character can't even do aerials xD.
If you want you can send me (or upload obviously) replays playing against ness or marth so I can tell you my opinion. Marth outranges lucario's fair. Bair hits him but if he reads it he won't short hop fair but punish with sideB. I could write a lot about that MU but i don't think this is the place and i don't think anyone will be interested neither xD.
If you try to hit marth with fair and he hits you with his fair, the problem is the attack you're choosing
If you try to hit ness with fair and he hits you with his, the problem is your timming or your position. Don't throw fair randomly but try to see when he can't do anything to counter it. Ness is sooo limited (unless you're shaky or fow lol)
Thanks for the awesome comment and I will sure try to correct everything!