5:30-6:05: I felt like you were playing too passively, you weren't really throwing, or charging needles, just kind of standing around doing nothing... until you chose to jump onto the top platform;(were you trying to get the super read on a waddle dee toss? idk that move is really slow, plenty of time to shield it.) that was a horrible decision, Sheik doesn't really have strong landing options, ESP vs D3 who has that 10KM grab range and of all places you decided to put yourself above him, all he had to do was walk underneath the platform and shield... he got 60% off of you from that. (I'm including the damage you took trying to get up off the ledge because had you not jumped on that platform you wouldn't have ended up on the ledge in the first place). one thing you can do in that situation when they aren't super close to the ledge is do the jumping get up in order for them to chase you into the ledge, then DI back into recovery chain range, chain to the ledge and roll up.
6:05-6:20: When D3 bairs your shield, either try to grab his foot, aerial OoS, or maybe try and f-tilt, Shield drop jab isn't going to cut it in that situation lol. Also when getting D-thrown by D3, if you aren't a chaingrabbable character teching in place is a horrible option, it literally lets him CG you. if you tech away he cant punish it without reading it prior, so that's generally the safest option. You can also try waiting a bit then rolling behind him if he starts to move towards you. But yeah teching in place is bad.
6:20-6:38: You actually played this portion pretty well, until you got your f-tilt off, running upsmash is not a safe followup to f-tilt, granted you did hit with the second part, but only because he dropped his shield prematurely to try and grab or something. if you have to dash then Shield dash grab his landing, although you probably could have walked a little forward and caught him out of his air dodge with f or u-tilt. also you messed up your punish on that D-tilt you shielded, I personally would not have expected a second one either, but i also don't think i would have gotten hit by it, from the distance you were at + it not being a power shield I would have either shield dashed or rolled away. unfortunately he just didn't fall into your immediate punish zone from that position. Sheik has a hard time getting up off the ledge, but that was a definite read by Keist. Getting read happens, had you waited a little longer to see if he would take immediate action may have saved your life, but like i said getting off of the ledge sucks. You most likely were going to die there lol.
6:40-7:00: after you got the bair wall bounce (technically it was a stage spike but since he didn't really go down I'll just call it a bounce) you should have double jumped back onto the stage instead of throwing out a fair that couldn't hit, even after you miss the fair had you used chain to recover there instead of vanish you would have made then it back on the ledge in time to punish his recovery, as a result of getting stuck on the ledge with vanish (intentional or not) you got hit by a star then forced off of the stage. Nice job getting back on... but that's dangerous territory to be in.
700-7-30: You kept trying to punish his recovery and get ups with dash attack. I'll break that down a bit more, you were trying to landing trap a character with 5 mid air jumps with a move that if missed leaves you vulnerable for like 10 years. And you also used that same move to try and punish his get ups... get ups have invincibility frames, meaning there is a definite chance of missing the punish, so why take that gamble with a move that if you miss gives the opponent enough time to put the controller down, take a few laps around the room, sit back down, wipe off the sweat, pick the controller back up, and then think about how to punish, and then punish you. your tilts are much better at landing, and landing a tilt leads into a lot more than landing a dash attack, and missing a tilt has a much smaller window that you can be punished in. All in all there is pretty much never a reason to use dash attack unless you have no other means of reaching them... and even then a half way charged needles is probably safer and more worthwhile. Any way those dash attack cost you like 50ish damage... fresh u-tilt kills around 85 on this stage. you probably should have died but it looks like kiest messed up an input and landed with dair instead of bair, and seeing as you didn't shield at all its obvious the bair would have hit you at a horrible angle and he would have had an easy edgeguard against you. Oh well he did miss, then some stuff happened and you got a kill. Good job.
7:30-8:10: I saw you start up a vanish while he was sill invincible... lmao. Then you tried to f-tilt lock him starting at 0%, learn f-tilt percents F-tilt doesnt safely combo into itself until around 20-30% for a general rule of thumb, (You could have however, u-tilted, grabbed, or d-smashed, if you had wanted to be fancy you could have done f-tilt jab 1 jab2, then f-tilt/grab... but f-tilt x4 wasn't going to work... and it didn't work) That right there lead to you off the stage getting destroyed as you tried to get back on. then after you got back on you failed a punish on a missed Dedede dash attack( a bette rpunish would have been instead of just walking back and forth and then dash attacking to just run and grab him, teched his dthrow in place again, got out, and jumped back onto a platform. and Died. that entire series of events I've already explained in different sections of this critique about why they are bad, so if you aren't sure go re-read the post.
8:12-9:10: First you did absolutely nothing with your invincibility frames, you walked around underneath a platform and waited until your invincibility ended before you started charging needles. then you land needles and follow up with dash attack, a throw would have been a better option, he teched back into you and i guess because you were jabbing the waddle dee you ended up triple jabbing... that's not really the strongest of punishes but that's fine at least it didn't get you hurt or anything. Then you dash attack his shield, tech out spot dodge a grab whiff 2 grabs in a row then get grabbed with your back on the ledge. Then you got D3 dash attack on the ledge, luckily you were only at 30, but Dash attack should never land on characters that aren't chaingrabable. Then you got knocked off stage and managed to only take a get up attack while getting back on. Nice f-tilt to running upsmash, although its a shame D3 is so fat and you were moving since the double hit probably saved him.. he might not have died anyway since D3 is fat. next you mess up a gimp attack, and once again find yourself on the ledge. you get faired during your get up and eat waddle dees as you desperately try to get back on. Kiest messed up another bair and u made it back on intime for the stage flip.
9;10-end You mess up another punish... and it looks like you've completely lost it, you're just throwing out bairs, until he punishes it with forward roll into grab, then he trips during a sure fire punish, and you try to double jab into vanish... That doesn't work, if you have any delusions of that working, discard them immediately. I'm somewhat mad I even saw you try that tbh. Then you get edgehogged as you try to get back.
That's all I have time for right now, I may or may not critique the rest of your vids when i return