Well, it really depends on the production - and in the film/tv business you have many combinations.
I'd really need to see the rest of the credits for that particular production because there might have been one for 'Regie' separate from 'Redaktion'.
In normal day-to-day parlance in a German tv station, the word 'Redakteur' is used (for documentary films) as I describe it, not 'Regisseur' for, for instance, 'Land und Leute' films.
It's also used where in the US we would use 'TV-Reporter'.
One reason it gets complicated is that through the years, as film/equipment has gotten smaller, less expensive, and simpler, a documentary can be shot by one person, so that one person could be responsible for the editorial content, direction, camera, sound, and editing.
In any event, a Redakteur is always responsible for the editorial content and tells, not asks, an editor (in this sense the person cutting the film on, say, an Avid), what should be in the final film since it's his/her project.
He/she has proposed it, gotten the go ahead from the 'Abteilungsleiter' - for a sports film, a cultural film, whatever it might be.
The 'editor (again, the person who physically cuts the video on the Avid)' has no 'editorial' (i.e., anything to do with the content of the piece) say.
In some tv stations, the editor (again, the person who cuts the film on the Avid) might have the right to refuse to work on a film if the Redakteur wanted it cut a certain way which might damage the editor's technical reputation, but the Redakteur is always directly responsible for the editorial content and no one else.
You do run into a problem where a Redakteur is in charge of a whole department, say the Redakteur in charge of travel films for a public station.
He/she obviously can't make them all so will assign a director who, in turn, chooses a cameraman/woman, soundman/woman, and so on. The 'Produktionsleiter' arranges hotels, etc., the 'Produzent' in this case is the tv station which has put up the money.
Since the Redaktion, in this case, has a content supervising function over the entire series, you might run into a credit situation which says: Redaktion: Ralf Schmidt, Regie: Norbert Beilharz, Kamera: Helmut Kohl, etc.
In no case is the Redakteur/-in responsible for physically 'cutting' (on an Avid or FCP) the film unless he/she has agreed to take on this additional responsibility as part of his/her contract with the tv station.
Cutting a film on an Avid is a job for a specialist.
Researching what's happening in labor relations today as compared to what happened in labor relations in the 1930s is a job for a journalist and historian. The film/video editor knows his/her machine and seldom much more. He/she is a technician, not a journalist.
The Redakteur knows what should be in the film in terms of its content, who should be interviewed, what archival footage should be used, what should be filmed on a picket line today, etc.