To control the robot I designed a program that gets the subscriber amount from my channel URL and then sends it every second to the COM-port that is connected to the Arduino. The Arduino than reads the received string and reactions accordingly to it. I used a 30A brushed ESC as power supply to get the 5 VDC for the servo's.
STL and Fusion 360 source files can be found here: https://bbprojects.technology/collections/stl-fusion-360-source-files/products/subby-the-interactive-youtube-subscriber-robot-files
link to the build video: