This is a theme that can be applied to the Google Chrome extension called "Controls for YouTube"
当前为
The latest version of the Controls For YouTube extension now includes an option to change the buttons to double-arrows, so you no longer have to keep this userscript installed. Make sure you have updated to the latest version (1.32 or higher) then open the options page of the extension and change the Button Style to "Rectangular Buttons" (picture below).
Old information...
Controls for YouTube is a Google Chrome extension which adds... controls for YouTube. Specifically, it adds fast-forward and rewind buttons over by the other controls. I made this userstyle so that those buttons more closely match the original YouTube interface. You MUST have that extension installed in order for this to do anything. I am not the author of that extension, so I cannot help you if you're having issues with it.
Install the extension from here:
https://chrome.google.com/webstore/detail/controls-for-youtube/doocmbmlcnbbdohogchldhlikjpndpng
Make sure that the buttons are enabled in the extension's config screen. I forget if they're on or off by default.
