BTW, I am a huge fan of visual storytelling. Even a slightest of details make the difference between the world being alive and it being slop. It is a known fact, that the bending styles were inspired by martial arts, and this demonstration is perfect for showing why that made so much difference.
pinacle of an example.

The lightning in the show was always treated as a dangerous art, that can hurt the user. It cannot be held, only directed. And the visuals had to show that
1) Azula is pointing. Her fingeris slowly sweaping through the air in the oposit directions slowly gathering the charge from the environment. She is "scooping" the lightning, but never golding.

2) The only part, when she actually stops moving is, when she puts her fingers together to finally direct the bolt away from her. Before that, she had to go with the flow.

And now, compare it again to the shit above.
The summoning of lightning itself was instant. She does NOT need go gather it. After that, she holds it in place for several seconds to show to the audience, that the blue balls are harmless.

Only after the blue balls are shown to be harmless, she starts the dance, that is NOT increasing the lightning in intensity. Then she puts the fingers together. Again, with no lore reason I can see.

That is followed by the only real piece of visual storytelling I actually saw in this cliip. She looked at her hands for a moment. That implied, that she was actually surprised by the result. Although, I do know that was not the intention.

So, after she played with the blue balls for so long, she finally throws them at the temple.

What a disaster.