Yes, but, from what I understand, the video does not explain how we can transfer custom-state data from reusable to reusable. I.e. it does not explain how to “set state of RE2 when state of RE1 changes”. It just explains how to “send state of RE1 to the main page” which I know how to do, but I do not know the next step: use that state to set the state of RE2. having one reusable inside another does not work either (see edited editor)
or it might be that I am just too confused to understand it
In your case the relevant ones are the first two. In either one of these you will need to set the state or set a url parameter. And set the search constraint to the chosen one. No need for the event trigger.
I recommend for you to watch the video and focus on how search is constrained and how states or url parameters are passed. If the video does not cover it fully then research how custom states and url parameters work (focusing on how they are passed and “seen”). Even though the video is about how filtering work using Canvas assets, it does a great job at explaining most of the above concepts.