[partially lost] European Mario / Zelda NES crossover

A while back, I saw a video of some (I think German) person, playing a Mario / Zelda NES crossover. I had never seen a game for the NES like that, anywhere. And i downloaded it (I often download videos i find interesting) as mp4 to my desktop. Recently, I decided to look into this game. I looked around google search, but I couldn't find any information on a Mario / Zelda crossover for the NES. I have now uploaded my downloaded video of this to youtube. Any information would be appreciated, I am not very experienced in these kinds of things. I have the video of this linked down below, please watch it and let me know if you have seen a game like this anywhere. I am under the assumption that this game might have only been released in Europe.

Sorry for the bad quality, it is all I have, here is the link: https://youtu.be/IVg-he-eyEU