I remember those days when videos on youtube could have movie playing in a moving small rectangle bouncing around, this was done to avoid content id systems I guess. Then some movies were reflected as well.
This is still a thing for Japanese game shows on Youtube. (For some reason Japanese TV channels try their very hardest to prevent people from paying to watch their content if they are outside Japan.) Example: https://www.youtube.com/watch?v=ApNCpZJawsw (from about 2 mins in)
I am sure content id system within youtube would be very sophisticated. But if I were to solve this problem simply. I would first detect edges of all the rectangles within a video. Then get a normalized RBG color historgram for a N seconds of the rectangle forming a timeseries. Then do a approximate time-series matching over all content in my database. I am sure this simple algorithm could be highly optimized further. Is there an opensource library which does something similar?
It is traditional arms race. The whatever system combats something is constantly improved. And the other side consisting hundreds or thousands of people try to circumvent it all the time. Not too rarely they find some new way and that then has to be blocked.
