Unfortunately, tutorial videos on 2A are really terrible, nowhere close to anything as detailed as the other styles, which makes learning 2A more difficult. Some good ones would exist for the basics like the Dazzling Dave video you’ve found, but progressing past the basic 2 handed loops into other tricks like tanglers would require a lot of figuring out on your own and asking the community for help. The thing is, 2A tricks require little explanation, you look at them and you know what you need to do and what movements you need to make, but then there’s a lot of hidden complexity and details that go into those movements that you have to refine over a long period of time. Then, once you get the trick and can do it forever, you tend to forget all these complexities and details because the trick just comes naturally to you. Because of this, you probably won’t ever forget how to loop after you’ve learnt it, just like how you won’t ever forget how to ride a bike.
I think the Dazzling Dave video covered most of the tips that you need to know for 2 handed loops, though I’ll add on that a shorter string is very, very much preferable to a longer string. It’s much easier to make the yoyo loop downwards than it is to make the yoyo loop upwards. If you find that you have trouble controlling your loops, make life easier for you and loop with string as short as 70cm. Either way, once you get it, you’ll be able to loop on longer strings with no issues. Also, the looping movement is about the flick of the wrist, so your arm shouldn’t move much, if at all. You can see Dazzling Dave’s elbow staying at pretty much the same position while he is looping and only his forearm and wrist are moving. If you find yourself moving your whole arm, stop and concentrate on using your wrist to loop.
This is a common issue for lots of people that just start out with 2A. Even if you’re a 1A professional, you’ll probably run into this issue, because you never really need to care about how to handle the tiny rebound when the yoyo hits the end of the string when throwing for 1A, or any other style really. Plus, those yoyos are unresponsive so they won’t return on such a small rebound. Heck even 0A fixed axle yoyos won’t have this issue. I reckon people who are experts at 0A would run into the same sleeping problem when they use a 2A yoyo.
2A yoyos have such a tiny gap and are extremely responsive, so even a tiny rebound from just throwing the yoyo down will cause the yoyo to respond and return to your hand. So what you have to do is to absorb that tiny amount of rebound with your hand. It will take a while, but when you throw the yoyo down, just a tiny bit before the yoyo hits the end of the string, pull your hand upwards a bit to absorb the impact of the yoyo hitting the end of the string before moving your hand down again. Basically, your hand follows the tiny movement that the yoyo makes when it hits the end of the string (hits the end of the string > yoyo rebounds upward > yoyo then goes back down) to absorb the impact and stop the yoyo from returning back to your hand. Once you get it, you’ll find that throwing a 2A yoyo will look kinda awkward and weird compared to throwing a regular 1A (or any other style) yoyo. Your hand will do an additional “bounce” before it settles, the hand movement similar to doing a pretty fast single boingy-boing and stopping. The reason why this doesn’t happen even when you throw with full force doing around the world is that the full force of the impact of the yoyo on the end of the string is gets converted into the centripetal force for circular motion. Hope this helps!
Oh I should add that you should absolutely take time to practice sidewinders, especially the outer sidewinders where you throw the yoyo to the outside of your arm (outside of your body area). The outer sidewinders are harder to do thanks to the awkward hand position, but you have to do them to undo the tension in the string caused by looping (other tricks are different). It gets much harder when you have to do them on a yoyo that won’t sleep at all. Learning sidewinders will make learning 2A much more enjoyable since you don’t have to stop what you are doing and let the yoyo dangle to adjust your string tension. Trust me, that gets old very quickly. Doing flying saucers or UFOs isn’t ideal as well since you have to change your throwing direction and can’t do it as quickly as sidewinders. Also, it’ll be hard to get a UFO to work when your string is way too tight since the yoyo just returns to your hand immediately. Practice your sidewinders until you can do them even if the yoyo returns unexpectedly or doesn’t sleep at all. It is almost essential that you know how to do them even if the yoyo refuses to sleep because as you loop on your left hand, the string will continually get tighter with each loop and it’ll become impossible to get the yoyo to sleep at all. Even the special throwing technique that I mentioned above will not do anything to help, the string has simply become too thick due to how tight it is.