I have found the true name of this camera. It's the Zeiss Ikon Zeitlupe. Here's some info from the wbpage of The Science Museum Group collection here:

"Zeiss Ikon 'Zeitlupe' high-speed camera. Model II, manufactured by Zeiss Ikon AG , Dresden, Germany, 1935. Outfit comprises two camera bodies, spare mirror drum, tripod with two heads, 1000mm lens and power pack.
A Zeitlupe high-speed cine camera, Model II, made in 1935 by Zeiss AG in Dresden.
The Zeitlupe or 'time magnifier' camera used a combination of a rotating mirror drum and continuously moving film. The maximum speed was 1,500 frames a second. A full load of film (180 feet) lasted just two seconds. Zeitlupe cameras were used to record the V-bomb experiments carried out by the Germans at Peenemunde in the Baltic during the second world war."

One was sold for 850€ at Live Auctioneers here I personally think it's a really low price for such an important instrument that also survived a World War

More info was found at this book, the link will take you to the page here where it mentions that a Zeitlupe recorded the photofinishes of the 1936 olympics at 1.000 FPS and, later in 1938 they achieved 3.000 FPS. I don't understand how this camera isn't more popular after being used in all of these special and unique events, it's such a fascinating camera. Ill post more info as I find it

More info was found! Here's a picture from 1938 of the camera being used to record bees at 1500 FPS!

There's one apparently at the Deutsches Museum

There's a book from Zeiss Ikon for sale on Ebay that describes the camera and the rotating mirror mechanism, sadly I can't buy it, as the seller doesn't ship to Spain, but he was kind enough to photograph every page in high resolution and upload them to ebay. Grab them while they last or send it to Buktus!