The usual caveat in these kinds of situations is that you dominated you opponent so thoroughly that it's hard to give general advice without sounding like I'm splitting hairs. The problem is, the dos and don'ts that I could give you are hard to see the reasoning for based on your performance in those vids, because your opponent had no idea how to punish the punishable things you were doing.
If your opponent is standing, it's generally not a good idea to throw out Paralyzer or Plasma Whip, as both are really easy to PS on reaction. Generally in those positions, dtilt, bair and nair are better. Some ZSSes also use fair. I prefer not to because of the landing lag, but it's really a personal preference kind of thing. You can use Plasma Whip to mix up aerial spacing in timing, but it usually shouldn't work. Your opponents didn't PS your moves probably due to lack of experience. I saw a lot of aerial approaches from your opponent in both matches, and that's not usually a good idea. A knowledgeable player will approach on the ground, and it's good to know your options against grounded opponents.
Usually, grabbing should be avoided except as a mix-up. Dash grabbing should usually be avoided altogether due to it's noticeable blind spot. In many situations where you went for a grab, a dsmash would have been much more apropos, as it only comes out three frames later, has less cooldown, a comparable hitbox, and always leads to another dsmash, and can usually be linked with fair for around 38 damage in a single go. More if you charge the first dsmash. I liked your use of grab to punish fsmash against the DK, though. That's an example of a good time to use grab.
Flip Jump is pretty much only ever good on the stage as a reaction to a laggy move that your opponent is doing, such as DDD's Waddle Dee Toss, or as a means to escape a combo quickly if an airdodge isn't going to cut it. It can be really bad for you to try to use it as an approach, since people who know how it works can punish it pretty easily, and if you get knocked off the stage out of it, you've lost a third jump, which is not a good thing at all.
I liked your use of uair and dash attack. When you used those, you looked like a ZSS main, since you used them fluently and knew when to back off. Keep in mind that those are two of your best and most spammable moves.
vs. 
