No focus depending arrow keys binding. Left/Right - always playback, down/up - always volume.
当前为
The youtube HTML5-player has 3 different bindings for the keyboard arrow buttons. The chosen binding depends on which of the player control elements has focus.
What is focus? The element is called focused if it is activated by mouse click or via keyboard when using Tab / Shift+Tab keys. The focused element has privileged keyboard control. For example if the play button is focused, then pressing the Space button will turn on the video playing.
In fact all these different keyboard bindings bring confusing as the user usually doesn't know which control element has focus (the indications are very poor) at the moment when he wants to use the keyboard.
So these arrow buttons 3 different bindings are:
1. If the volume control bar has the focus: left/down - lowers the sound volume, right/up - raises the volume.
2. If the playback seekbar has the focus: left/down - jumps backwards in the video, right/up - jumps forwards.
3. If any other control has the focus: down/up - changes the sound volume, left/right - jumps in the video playback.
This script has the goal to escape all this confusion: No matter which control has the focus - there's always 3rd behavior.
