You are right, just found a better video [1]. I did not realize that the person was moving their fingers under the cover. [1] https://www.youtube.com/watch?v=S

You are right, just found a better video [1]. I did not realize that the person was moving their fingers under the cover. [1] https://www.youtube.com/watch?v=S9VkV9RS-PI&t=45s https://www.youtube.com/watch?v=S9VkV9RS-PI&t=45s