Gorath summarized it well.
Still I tried a rough translation of the first making of video. Damn that was hard…

Still a lot of errors I guess. Enjoy.
Making of part 1
The TDE Universe
Intro:
Fantastic Worlds! The magic of enchanted realms, shining heroes and dark villans appealed from the beginning on. But who got bored by the books, comics and movies in the mid 70s started a new hobby: role playing games. But what RPG is, is hard to explain.
Florian Don-Schauen (Novel author, TDE editor):
What is RPG?
Thomas Römer (TDE chief editor):
…
Lena Flakenhagen (writer, TDE editor):
RPG is a movie in your head.
Florian:
A kind of improvisational theater.
Fabian Rudzinski (lead game designer Radon Labs):
RPG is what I do as my favorite hobby since 20 years.
Dr. Stefan Blanck (managing director Chromatix GmbH):
A game in a group, in a "fellowship" (some small community / as in Fellowship of the ring… ;D)
Thomas:
You sit together on a table. You move pieces (like on a board game), although you don't have them in your hand but only in your head.
Lena:
RPG is the novel you are allowed to play yourself.
Thomas:
You play a game, by personifying roles.
Bernd Beyreuther (creative director Radon Labs):
"You are Hänsel, you are Gretel (random names from a german fairy-tale) imagine…" - the famous RPG sentence.
Jan Hegenberg (scene musician & TDE fan):
That you try to suppress your own character and to play another role.
Bernd:
Then there is the second famous RPG sentence: "What do you do?"
Lena:
RPG is the cooperation of people who like to tell a tale together.
Florian:
We sit together in the pub at night and play how our characters get drunk. That as well is RPG.
And RPG was mainly connected to D&D in the USA. From 1974 on the novel game successfully integrated itself into the mainstream culture. (roughly translated)
Werner Fuchs (co-inventor "The dark eye"):
The origin of TDE lie naturally in its american role model D&D. TDE is nothing else then the german answer to D&D.
And what three inventors started at a kitchen table in only 2 and a half month, grew ever since.
Thomas:
TDE has grown massively over the years.
Werner:
We were busily launching new products. Adventures (Quests) were added, add-ons were published in 1984. With that you could easily see that it went well.
Florian:
TDE was formerly a world like many other RPG worlds where you went somewhere and killed monsters. That was generally the beginning of RPG, also the beginning of TDE. Bit by bit people realized that you could also do something else.
Werner:
More and more flesh was added to the skeleton aventuria.
Lena:
A lot of information was added. Many new authors joined the team. Which is something what made TDE alive. New blood (in the meaning manpower), new creativity and also new methods.
Werner:
A continuous development was noticed. It was more and more produced. A number of over 100 products was already reached in those times.
Thomas:
TDE is nowadays after Perry Rhodan the best developed fantasy world in germany.
This universe not only grew in content but also expanded to new media. Novels told new adventures. Card and board games yielded the TDE logo only one thing was missing.
Werner:
We were discussing in 1990, far too late, about computer games for the first time.