i'd like to point out that the concept of the fading nightmare is ~90% taken from soulchess. here is the ability tooltip from soulchess (without color codes):
The Fading Nightmare's destination is to disappear step by step. The blur adds an evasion about equal to the transparency in percent. Passing 75%, the Fading Nightmare will instantly die after adding 10% of it's remaining hp as Venomcounters to the opponent.
Every order given to the Nightmare vanishes it by 1% (max 40%, max 2 times per sec).
Being attacked vanishes it by 3%.
Enemy spellcasting vanishes it by 7%.
Winning a fight vanishes it by 4%.
Current Fading (in steps of 5%): 0%
the only real difference i can find are adjustments made for it not being turn-based. similarities:
-hydra model with black tinting (with increasing transparency depending on fading)
-evasion directly related to fading
-dying + damage/dot when reaching a fading-threshold
-increasing the fading during combat as well as by other actions such as movement-commands
-identical name for the unit as well as for the ability
do i mind? its not really a big deal since its just a single concept out of hundreds in soulchess alone and people inspire each other all the time.
still, i consider it a really bad practise to do this, especially since it was not a source of inspiration but a copy.
so overall i'm cool with that (it is a decent cinematic and i guess i should feel happy about you liking the concept that much) but i'd still like to give you some advise, for your own sake:
what you might want to do in general (not just for maps and videos, but for any content you create): simply ask the person if its alright to use their idea. unless you want to make money from it, the vast majority of people won't mind as long as you simply mention them somewhere. if they cannot be contacted for some reason, simply list them anyway.
why care?
aside from legal issues, getting caught can result in a huge negative backlash. a good example is the popular youtube matthew santoro, just look at these downvotes after he got called out by gradeAunderA:
https://www.youtube.com/watch?v=HyTaolpoOOg
as another example, since you are german like me, i'd like to point out how some of our politicians lost their "Dr." titles (alongside with their public credibility and sometimes even their position in the government) for not correctly citing sources. of course people are more strict when it comes to scientific publications, but the public reactions point out that many people frown upon this sort of thing.
so whenever you are tempted to do this, ask yourself if it is worth the risk and if it is the right thing to do from a moral point of view. you might find the alternative to be much better.