I do not say that I am doing the "correct" video, but I believe my way to do the video can be a helpful guide for others to think about how to communicate effectively.
In this case, I would first define a problem that related to "saving the planet." The problem can be particularly narrowed into a simple phrase. I would not choose a broad problem and try to compress it into a 2-3 minutes video because that maybe too short for a large topic. For example, I find the problem is that "Even most of adults do not care about saving the planet, so most of children do not even know about the damage that we have done to this planet." I would also define a keyword to target into a specific problem such as "Trash." This first part is to inform audiences what already happened. (Problem)
Then, I would create a "statement" as solution for that problem by researching for credible sources. I would also narrow down the solution into one single idea. For example, my solution is to teach children to pick trash then throw in trash can. The key phrase for the solution is "Start from small things." This part would inform audiences about what to do. (Action)
To motivate an action, I would create a certain feeling for the video which has odd scenes of children. To make it a bit like horror film. (No blood, or anything horrible but just the feeling of scene that is similar to some beginning of horror film.)