Ok, I'll do this thing now. This is probably gonna be long, but whatever. You asked for it!
0:07ish: you started out well, and you could've kept it going had you predicted him properly here. Most players won't DI into you after you've hit them a few times, so you're allowed to keep going agressive on them provided you predict their AD/defensive aerial correctly.
0:12: Why did you SL? It shouldn't usually get to the point where you take a gamble anyways, you should be in the air pressuring them out of their jumps/ADs, or using some empty jumps to get them to blow theirs, or at least attack earlier lol. Your other, more appropriate option here would be to attempt to grab as they land because most people do that instinctively. Should that not work, you can always chase a roll, or grab/Dtilt/Dsmash/whatever you want to a spotdodge accordingly.
0:17-024: why the down B? Unless you're just messing around, but this critique is serious, so no johns. I can forgive that first Dair when you got Uaired because it was a defensive more, but that second one needs to be planned a little. As you fall, don't go for a FF Dair because they have ample time to shieldgrab you, or Fsmash you apparently. Usually(but not always), you want to use a few of your jumps going down to trick your opponent into thinking that you'll drop when you actually won't. When you do decide to drop, you typically wanna FF and do one of a few things: Dsmash if they shield drop, Nair if they jump out of shield, grab if they aren't ready or continue to shield, or whorenado. There are more options at your disposal here, so don't be afraid to experiment.
0:28- a few extra Dtilts here. I recommend reading Emblem Lord's thread on Brickwalls and Setups for more elaboration, but MK only needs to use one or two Dtilts, then needs to stop. This is so that you can respond to their reaction. For instance, you could've SLed or Faired ICs out of their jump had you reacted a little quicker and hadn't been focusing on the Dtilt.
0:33- You had decent momentum going here, you should always expect ICs to do a Dair because it's pretty safe when challenged(I think lol). You can still stand under them, but be sure to either tornado(slightly to the side) , or SHAD to the side and punish the terrible lag.
That little skirmish you had from 0:45-1:02- too much down B! Not a great move imo. Anyway, you spacing was pretty good, but it doesn't do you much good if you aren't rewarded for it. If he's feeling comfortable and getting inside of your range, then you aren't making him uncomfortable with your pressure+range game. You need to get in those hits then space sometimes. I have no matchup experience here, but I would venture to say that you could just aggro ICs most of the time and be pretty safe(as long as you stay out of grab's reach).
1:20- You Usmashed when he was shielding....I know he wasn't right before you did, but if he doesn't ordinarily jump away at your approach(which I doubt most good ICs would), then you shouldn't run in to try that. Try a dash grab every now and then ok? Grabs are great setups(especially Dthrow) for MKs awesome aerial game.
1:27- There isn't any need to attempt to land on the stage like that if your opponent is that close. Try to use a jump or two to get him to whiff a smash before FFing to the edge or stage or something. You could also FF nado or just nado onto the platform. Options galore!
1:42-1:44- As soon as you see that second jump, you should already either be about to Dair/SL him, or that should be your cue to hit him again. MK is the best edguarder in the game, so throw yourself out there! Be sure to always predict ADs and learn to read his movements. It's not usually the best idea to grab the edge on an opponent recovering high anyways if they can make it because they could probably make it with or without you there lol. Just stand on the edge until you think the time is right to go for the kill(practice!).
1:47-149: Too many SHs man. After that first Fair, it would've been best to dash grab or set up a brick wall/Dtilt trap.
1:52- punish don't SH!
1:54-2:04- SH dair is good, but certainly not spammable. Switching up your game is essential, nothing else to it. Maybe a few Sh Dairs to an empty SHFF to grab/nado/whatever.
2:21-DJ fakeouts don't work bro lol. Just use a few jumps above or Dtilt traps to see what they'll do.
2:23-2:25- keep moving! Unless something distracted you, then there shouldn't be any reason to stay still.
after that-....FF your Fairs.
end-don't use Forward B except as a recovery move, and don't spam Fsmash! That move should rarely be used! It's kinda laggy(especially for MK), and has less killing potential than Dsmash. Just use it as a mixup, or when Dsmash is decayed.
Okay, I'm only doing this one! ...Unless you need more help that is. Do work with this man!
You also pointed out my main problem there: I need more experience with his move-set, as well as going against different characters. Jubilee was the first day I played Meta in a competitive manner, so I have a long way to go. 
