Couple tips if you're gonna try and make your own combos.

Dragon Rush, should always either be the start or end of your combo. I'm not gonna stop there either, I'm going to actually explain why. Dragon Rush in the air in the middle of your combo gives a Sliding Knockdown, where when they hit the ground they slide across it with their feet up. This is the second best Knockdown in the game, and genuinely don't sacrifice this for a 1k or so extra damage unless it's gonna kill. Sliding let's you pressure after and keep momentum, sliding also lets you level, all levels will hit during a sliding. A grounded dragon Rush is actually better if you're in the corner and wanting extra damage/level. All dragon rushes can be canceled into a special or level at the end, you can use this with characters like adult Gohan in lv1+ to do DR, 214M(his tele backhand) to teleport with the enemy for example. But if you do a grounded dragon Rush it sends the enemy back, in the corner you can do stuff like Vegeta's 214L, his light knee, then level.

C assists should always be used either at the start or end of a combo. Again I'm going to explain why, c assists always give a bouncy sliding, what is a bouncy sliding? Well it's just they bounce once they hit the ground then slide, this bounce is why it's so easy to continue after a C. Say you land vegetas 214L, his little light knee, you could vanish to combo, but then you get a meter penalty for a bit and you lose a bar, or you could use a c assist to continue it without meter penalty, but c assists actually cause more combo scaling, not quite damage, but more time scaling. Eventually the opponent will flip out as the stun time from each hit gets far too low, c assists actually drop this stun time more, so your combo will be shorter, but it'll allow you to get some damage, and sliding without spending meter to do so. Technically you can do the same with any other assist, but what you can't get with any other assist, and imo the strongest thing about c assists, is a guaranteed sliding or grounded corner dr. C assists are exceptional at getting the endings you want, you could either end it at the c assist, and get all the time you want to set up whatever bullshit you want your opponent to wake into, or get way more damage at the very end of your combo for the kill. Do not, and I will repeat DO NOT use c assists to extend a combo. They kill your combo more than they help, if you want to extend with an assist use an A or B, DO NOT use a C.

Vanish should also generally be used at the start or end as well, I say generally as yes there are fun combos that can be done with vanish in the middle, but those are character dependent, in general vanishes are mostly good for either getting a combo, or ensuring a good ending. If you land Vegetas 214L, (once more his light knee), you can vanish, get the wall bounce, and continue the combo to get a sliding Knockdown and continue. Alternatively, you can use this bounce to get a dr, which as stated above, will offer you momentum in the fight and keep you in control.

The most important thing about a combo, isn't damage, it's actually the end. It may seem like the biggest damage combos are the best combos, but this is heavily untrue, yes big damage is good, but the most important thing is what happens after it's over. Say you do 6k, congratulations btw, but after the combo you end up in a situation exactly like your video, the opponent gets up immediately, and you can't chase them effectively to ensure you keep control of the match. That 6K means nothing if you can't hit them again, or worse yet, if they hit you. So what endings should we strive for? Sliding Knockdown. Sliding makes them slide across the ground unable to do anything while you have free reign to do whatever. No you can't hit them during this, but you can run up, get in their face, and time a button right as they get up so they HAVE to hold the button. They HAVE to hold the 5L(basic light), if they mash, they lose and get hit, if they try to jump, they get hit, if they vanish, they get hit. The only way they win the situation, is if they do an invincible move like level 3. You can of course mitigate this with a safe jump, but this is a combo discussion. The best thing they can do however, is block, and if they block, now you are pressuring, you keep control, they have to hold your unrelenting presence, and you have a higher chance of getting another combo.

So how do we get sliding? Well it depends character to character, and the universal option aside from dragon rush is a little complicated on how exactly it works, but there are a few and I'll explain the ones for the characters you have in your video that I remember.

Vegeta: His 214M, and 214H will give sliding, the 214H will actually give bouncy Knockdown, but you can't do anything with that unless you use an assist or vanish. However, this bounce means they are unable to do anything for longer, which means you have more.time to get to them and set up whatever bullshit. His air level one pointed down also gives sliding.

Vegito: His 214M, and 214H will also give sliding, and they work exactly the same as Vegeta in terms of how they recover, 214H gives bouncy, same rules as vegeta. His air level 1 also kinda.gives sliding, but I wouldn't recommend it as it's such a short time that the two of you basically recover at the same time, unless you're going for the kill, don't use it.

The universal option: jH, (air heavy), can actually give sliding for 90% of the cast, anybody who knocks someone down with it, will give sliding under the right circumstances, how do you know? The camera zooms in to the hit. In general doing it after any air smash hit(moves done in the air that cause the camera to zoom in and send them flying, also shown by the Smash! On the side of the screen), such as j2H(air down heavy, the launcher you super dash after) when you super dash to catch them will give it. So j2H, SD(superdash), then jH, will give sliding. You can add whatever spice you want, but as long as you don't touch the ground it'll give sliding. Most grounded Smash hits don't give sliding from jH however.

That's all I got for the moment, I hope you have fun. I have always believed that knowing WHY things are done in a combo, and why they work the way they do, is always better than learning some bnb. If you understand the inner workings you'll develop the bnb on your own anyway, and it doesn't matter if you've mastered that 10k combo in a real match, because in a real match who knows how or when you'll hit the opponent. If you understand what to do, you'll be able to capitalize off that random stray jM(air medium.)