If you look at 1:36 when he presses the home button. Then press "Audio", you can see the screen responded that the button was pressed. BUT the screen has a "phantom finger" that kept pressing "Text" then the "Phone". Then again when he press home. You can see that a "phantom finger" is repeatedly pressing around that area very rapidly, which causes the "unresponsiveness". Even though you can see that the screen did response when he presses other buttons. The OP's "phantom finger" doesn't press as rapidly as this guys' when the screen started to respond. lol
https://youtu.be/VJ00b7mN36M?t=96