[homagetogorto]

To me, that suggests a "Waiting For" action -- waiting for completion of project "Research video tutorial software". I would just put this action in each of the three projects that (may) need it, but only flesh out the details once, in the "Research video tutorial software" project.

Maybe "waiting for" isn't the best phrase since you're waiting for yourself, but my point is just that you put a placeholder.

Sure, you'd still have to check this item off in the three projects that were waiting for it, but the last action in the Research/Decide project could be to mark it done in the projects that depend on it so that their Next Actions become available.

Sure, some kind of automatic linkage might be nice, but then again, it might be really confusing and the workaround is pretty straightforward. And certainly easier than fleshing out all the details in each of the three projects that might need video tutorials.