Just for reference an explanation from the video docu which accompanied the initial release a couple of years ago. The forum and the content are separate. The content is stored on common platforms (i.e. google drive, ...) and anyone with the share link can access it. The server owner (domain owner) is usually known which gives a contact to report this issue to. Just the forum where these links are shared is hidden behind anonymity and prosecutors like BKA try to catch the people responsible for its existence. The latest release showed that reporting the content was an effective way to reduce activity in these forums and some even closed outright.

The goal isn't to delete the content directly. A reporter team of two was able to automatically compile a list of links where the content is hosted. Sending these lists to the cloud storage providers proved a very effective way of "deleting" it. Apparently they are required to delete such content once it is reported to them. (Iirc this was under european law.)
And to answer your point, sending emails to server administrators should be within the legal capabilities of the BKA.

This undeniably binds some resources of the BKA. They were open in communicating this and if I could give the required money and personal to them by voting I would. Unfortunately raising awareness for the issue is all I can do at the moment, as there is no election here in the near future. Let's hope they do as they said and adjust their processes in this regard. A compromise could be that the content is reported after the legal process from closing the forum is complete.

Technically correct but the reporter team mentioned no trouble in communicating the issue even to international providers as the content in question is stored in the clear net where contact information is no secret.

And to your last point I totally agree that a combination of issues is likely the reason nothing is done about it. But they keep promising that they will change this. Unfortunately a two person team showed that there is a difference between saying processes would be changed and actually changing them.

I also don't agree with the initial premise of the prior comment, that "people in power" don't pursue predators with intent. Seemingly I overestimated how relevant this example was to the premise. To me the fact that a seemingly easily implementable solution not used to full effect is all I am mad about. I don't want this platform to become a right wing conspiracy platform either, too many exist already.