Frame count of 1:09.950 on Avidemux

Frame count of 1:09.967 on YouTube Frame Timer

I've tried using Gamepad Viewer for my NES controller, but only the A and B buttons show any activity while the Dpad, Start and Select buttons don't show any response even though the page itself shows activity in the remapping section. I've tried remapping and still no Dpad, Start and Select.

Are there any decent alternatives I can try instead? I'm using an original NES controller plugged into a Retroport USB adapter into a laptop running Windows 10.