I am updating this thread. There is big chance that this video is half hoax. But not entire video just Tito selling Potočnik's plans and Yugoslavia having space program.

Herman Potočnik on the other hand is real character and he realy made book about rocket motor's, space rocket's and space station's which influenced future rocket engineer's. He is considered as one of the founders of astronautics. He made his book in german language becouse he was studying and living in Vienna. Book is called;

Das Problem der Befahrung des Weltraums – der Raketen-Motor (The Problem of Space Travel – The Rocket Motor)

Additional wiki link;