You should just take a break. How much of the other smashes have you played? If you're really into the series as a whole then you'll probably end up wanting to come back to the game after a certain point. You should also keep in mind that losing gets you better faster than winning. Looking at your video, it seemed to me that you would benefit from playing better people (that ZSS didn't particularly impress me). Of course, that would result in losing more--but again--that's the best way to get better: playing people better than you.
This is true. However, let me also point out that you will improve this way, if you don't learn anything or fail to understand what you did wrong, then this method will actually be of no help to you. Getting better at any game like this though is through trial and error. You want to get better? Well, you have to first really suck at the game. Let me provide you an example of something. I'm sure many of us have played some insanely hard platform games. Some of the levels just aren't fair, right? And they're ridiculously hard. When we first went through that level, we couldn't do much and died almost right away. You don't give up though. As you keep dying, you start noticing more and more about the level and the way it's laid out, and because of that, you're slowly making more and more progress because you are learning about the game's conventions and how to overcome the level through means of trial and error. Soon enough, after you've died 300 times, you can now beat the level. Here's where this gets fun now. You beat the level once, and every subsequent time you go through that same god forsaken level, you beat it more quickly, with less deaths, and with far more technique and skill than compared to before. After all that time spent with the level it becomes trivially easy to do and it's not a problem anymore. This sort of thing also overlaps with something called "training from Hell".
I'll provide a personal example now. I'm pretty good at Smash 4, but I wouldn't be as good as I am now without a friend who would ONLY play me in Super Sudden Death back when Melee was the latest game. I lost many times to him, and since there was no reasoning with him, I had to learn how to defend myself the hard way. This paid off because even though I kept losing to him, I kept doing better and better every time. It's about trial and error, and being able to learn from those errors.
That will bring me to another point. You WILL lose games, even if you are really good, however, you must learn how to be an honorable and graceful loser. Your opponent did better than you, so congratulate them. Don't cloud your thoughts with hate or anger, because then you get frustrated, you start playing worse, and your skill growth starts stagnating because you're unable to learn from your matches. Don't let the mental fog of war keep you from improving.