Hi Chandy, well i noticed a lot of small, easy fixes you could make to your game that would make a HUGE difference and you probably would have gone to last stock vs his metaknight both games and could have won if you work on them. I call them "easy fixes" because they are DK specific and require no change to your fundamentals. You have great fundamentals so no need to critique that at this point. Also, Nannas gave great advice regarding more fundamental stuff as well.

Well, here they are, in no order of importance. Please excuse any bad grammar, I'd rather give you a **** load of information with bad grammar/run ons than a brief summary with perfect grammar that would take just as long lol
Ill start with the simplest thing. While this may not be as important as the other things im about to tell you, you need to JC more of your grabs, especially out of a dash to punish a laggy move because it has more range in front of him so you can actually grab earlier than if you did a dash grab. only dash grab when juggling if they are too high to do a jc grab because the dash grab has a higher hitbox, so you can grab earlier in that situation as well, where if you wait for the JC grab they may be able to jump out by then. Dash grab is also good for techcasing sometimes if you are a little ahead of them because the hitbox is also a little behind DK.
Example of when you should have JC grabbed(there may be more, but this one stood out for me): 9:32 you probably, if not definitely, would have got him if you JC grabbed. If you hit that grab, it coulda been a game changer which shows why it's worth mastering.
***Important section I noticed you flubbed many follow ups out of grab, mainly in crucial/ game changing moments, and you also often didn't get the most you could possible get out of a grab. Before I mention timestamps, I want to share something that I HIGHLY recommend all DK players to do, which is the reason I rarely flub my cargo follow ups. That is when you grab them, look at their % right away. There isn't much risk to glancing away from the characters because if you think they will mash out, press forward to reset the timer. This does many things. First of all, you can instantly judge how long you can pummel them before going to cargo hold. Second, if you look at the % right when you grab them, you get all of that extra time to plan what your best follow up will be at that percent and imagine if it will work or not. For example, if you did this at 3:16, you wouldn't have panicked and done a non guaranteed throw option. In that situation, it was best to pummel 3-4 times depending on if they were mashing (I often actually LOOK at their controller lol) and then do a standing cargo up throw to double jump up air and it would have killed. This strategy also helps when trying to judge if they are at too high % to do cargo up throw to fair or a combo of the like. Abuse that timer reset and hold them as long as possible until you think of a guaranteed follow up, you will definitely flub less grab combos if you do this.
Also, I noticed you sometimes up throw-up air too much. In some cases, you did it at too low of a percent. So low that the lack of hitstun from the up air would allow you do have no guaranteed follow ups. At low % v.s. MK, and many other characters, up throw to up air may not be the best option at low % for that reason. Try mixing it up a little and do a standing cargo f throw toward the middle of the stage. There's many more follow up options at that %. Always dash immediately after the f/b throw and if they DI toward you, you know the drill. If they DI away from you, you will have already dashed so you are in an EZ mode position to techchase. A dash attack is also great to punish a missed tech if they DI away. And I'm sure you know how many follow ups can come out of dash attack as opposed to just getting one up throw to up air. ***
Miscellaneous:
you jab a lot, which is great, but there were many situations where a grab was the superior option, mainly at high % when a grab was a free kill. Sometimes when you are going for the kill, you space aerials instead of go for the grab. 5:14 you could have turned around JC grabbed
Use more cargo up throws instead of f/b throws when going for kill combos. I'm not saying NEVER do f/b throw, but there were situations where u throw had guaranteed follow up to fair. Just master the % ranges by trying them out more. F/b throw works on lesser level players, which is a reason I used to have that habit as well. It has been working less and less the more I play higher level players who can DI quickly on reaction.
Since DK's neutral game isn't the greatest to say the least, it is necessary to get as much as you can out of grabs. You have great combo ability Chandy, but being able to combo and being able to always combo are two different things. Master those grab follow ups, and your punish game will be THAT much deadlier because a punish will always result in a ton of percent or even a stock.

Also, while you may have flubbed due to nerves which I obviously understand, that is not an excuse because if you master something, nerves won't affect you. Do that strategy I said about looking at the percent while grabbing and taking your time. No matter how nervous you are, it's harder to flub a combo if you do that
Hope this helps man, I enjoyed writing it because it made me realize some things I do sub consciously. Looking back, this post could even be considered a DK grab guide lol. Sorry if I drifted from subject to subject, I just had a lot to say and I wanted to type fast so I didn't forget any of it.
Lmao what a long post, IDC though I enjoy thinking about these things