https://www.youtube.com/watch?v=Vk1zyG3L9i8
Please give me advice, I struggle with the Snake matchup.
I think you lost more due to your overall gameplay rather than the matchup; your neutral and punish game could use some work. I can explain each to some detail:
NEUTRAL
Right off the bat I notice that you go for SH nairs and fairs too often. The Snake player didn't punish those approaches often enough but when he did he was able to rack up good percent or get a sticky on you. This is probably the biggest mistake I see many Meta Knight players make in their gameplay: using SH aerials too recklessly as their main approach. MK's aerials are good but he's no Fox; SH nair (the major offender) isn't safe on shield and should be used
sparingly (namely, when you read your opponent's jump or SH aerial).
I firmly believe that the best way overall way to play neutral is to play it kinda like Melee Marth: use MK's amazing Dash Dance and speed to bait and punish with pokes like Dtilt/Ftilt and combo starters like grab/usmash. Against most matchups you have to take advantage of MK's great ground game to get the approach. Your goal in neutral is to bait the bad approach and get your opponent either offstage (and use MK's amazing edgeguard ability) or pop them up in the air above you (and use MK's godlike juggle ability).
As you work on MK you can incorporate other things like using multi-jumps to "hover" and punish with a dropping dair or bair, and using Dimensional Cape as a mixup approach, but the Dash Dance bait-and-punish is the absolute core of MK's neutral. I'd highly suggest starting there before attempting the more advanced stuff.
PUNISH
Gonna give a few examples from your video but it's all about optimizing your punishes by keeping the juggle going and finishing off with a strong aerial (Dair, Bair), shuttle loop or down B:
00:42 - here you got a good dtilt hit which popped him up right onto the left platform (AND he didn't tech!) and you could have gotten a solid juggle string going if you opted for the Uair instead of the Fair. I know you didn't expect that reverse hit but I think even if you had sent him forward it wouldn't have amounted to much (maybe an IDC followup but it doesn't seem you use that yet). Juggles are a huuuuge aspect of MK's punish game, so if there's an opportunity to keep your opponent above you then go for that option.
02:25 is another good example of what I'm talking about; you got a good juggle going with the two Uairs and that Utilt trade, and you definitely could have continued that juggle when he landed on the right platform with another uair or utilt instead of going for the early UpB.
4:42 you had such a good combo going with the forward throw into his own mine and chasing with Uair. An earlier Utilt on that right platform would have definitely gotten you like an extra 40% + and UpB or DownB finish!
05:43 you got a really good one here though. He DI'd the Uair well so that Bair finisher was the best way to end that string, good stuff.
01:34 - MK is one of the few characters that can go out offstage to challenge Snake's godlike recovery. It's a good idea to get a feel of your edgeguarding range (the range where you can go offstage, get your hit in and come back onstage safely). If you can read where snake will try to set up his C4 self-explosion or his trajectory from that explosion you can definitely intercept with a good Nair or Bair rather than Fair. You did this at 04:34 which is great, keep going for those!
As far as Snake-specific advice, always be aware of Snake's mine and C4 placement. For the mine remember you can always just run in and shield to remove it. MK's poor bad tech stats make him a prime target for tranq techchasing (which the Snake did on you really well game 3). If the Snake knows his stuff a grab will lead to a tranq which will lead to a sticky, which is a death sentence. Lastly, against a grenade-holding Snake try to space your attacks so you hit with the sword tip to prevent hitting the grenade or getting hit by its explosion. This holds true for Uair and Dtilt especially.
I may not have elaborated well enough but if you need clarification on anything I said just let me know. Hope this helps.