The video link in your post is broken. Can you try posting it again? Also, can you provide me more details about your setup (e.g. how are you powering everything)? What are the current and voltage rating for the stepper motors you are using? What did you set the current limit to on your A4988?
By the way, you should be measuring the voltage from the potentiometer on the A4988 board, not the resistance. I recommend watching our stepper motor driver video, which shows how to measure the VREF voltage and set the current limit on one of our stepper motor drivers. You can apply the same method to the A4988.
I cannot understand what you are saying in your video, but I did notice the bad behavior you are seeing in your setup. Please answer all of the questions in my previous post. Also, can you post close-up pictures showing each of the A4988 boards that you are using in your setup?