This extension is about using the arrow keys on Youtube.com.
The goal of FocusTube is to increase your Youtube.com experience by making the left and right arrow keys of your keyboard navigate the timeline and the up and down arrow keys raise and lower the volume – all the time.
Let’s say you’re watching a video and want to rewind 20 seconds and also raise the volume. If the first thing you do is trying to use the arrow keys, this extension is for you.
Problem is, if the focus is currently not on the (HTML5) video player, up and down arrow keys are now scrolling the page instead of raising and lowering the volume, and if the focus is on the volume widget inside the player the left and right arrow keys are now raising and lowering the volume instead of rewinding/forwarding the timeline.
You have to either cycle using ctrl + tab keys, which is tedious, or use the mouse and click below the timeline of the player to make the arrow keys work again as expected.
What this extension does is it focuses the video player every 10 seconds, but only if the player is visible. That way, you can be sure the arrow keys work as expected all the time.