What cost you the most during your match was your airdodging when you were landing / coming back on stage. Examples would be at 0:46, and 1:12. In fact, you have a habit of
only jumping up from the ledge. You need to mix up what options you do off the ledge: roll, normal get up, the rare get-up attack. The Richter wasn't really going for holy water setups at the ledge, so you have all of those options available to you. If an opponent picks up on that habit in a match, they'll nail you every time.
One of your other habits in neutral is to jump high and space out an aerial / prepare a projectile. This isn't bad if you're doing the latter, especially if you want to avoid Richter's cross or other long-distance burst options from your opponent. But you should try to short hop into your approaches more, as they become faster and tighter. Along with full hopping in neutral, you also like to use your double jump haphazardly, and you can see this is actually what cost you the match when you used your double jump in neutral and didn't land on stage. If you want space, try simply running backwards and throwing out a B-reversed arrow or boomerang.
From your spacing it seems you get a bit tunnel visioned, meaning you tend to keep your eyes on yourself instead of your opponent. This means you throw out some moves don't really seem to be aimed at where your opponent
is going, but rather where
they are. An example is 0:24. You run forward and throw out a Nair, but the Richter is already jumping forward and has basically crossed you up by the time you stick out your foot. You can see you land with your Nair
where the Richter was before he jumped, while if you trusted your reactions a bit more, you could pull out a Dair instead and hit him while he's running/jumping beneath you. You can also see your opponent does a much more exaggerated version of the same thing, in that same instance. Notice how badly his Fair misses you. He was aiming at where you were a complete second ago.
Also study 1:42, where you don't watch your opponent so you don't see he's starting Holy Water and you jump into it. Watching your opponent will let you notice the startup animations of all of their attacks, allowing you to effectively react faster to what they are doing and counter appropriately.
You also give Richter way too much respect at the ledge. Notice how you just back off at 0:30. Later when you knock him off you pull bombs, which I agree with because they're a great tool for edge guarding, but you just stay far away from the ledge while you do it when you don't need to. If you were right at the ledge, Richter would have to worry about the bomb
and then you if he gets past that. In this match, he only really had to worry about the bomb.
All in all, you're doing some good things. I just think you should take the time to work out tighter approaches in neutral, and seriously work on coming back on stage from the ledge / landing from juggles. I don't like a lot of your directional air dodges (especially the ones tilted up: why give yourself more time before you can land on stage again?) but your ground play seems decent. Final example: if you want to approach with Nair, try running forward and short-hopping into it so your opponent has less time to react to your approach, as opposed to full hopping into it or (even worse) double jumping into it, as that is slower and gives your opponent more time to see it coming.