If the hotkeys are not working for you verify that they are set in the extension tab. To do that, click on the chrome menu (3 horizontal stripes on top right) and go to tools -> extensions. Scroll to the bottom of the page and click on "Keyboard shortcuts". From that popup you can change the keys to those of your choosing.
This extension enables you to control the basic features of online media player hotkeys via global hotkeys. Pressing a hotkey will trigger an action in the media player's tab. There are 4 actions bound to the following default hotkeys:
Play/Pause: Media key play/pause
Play Next: Media key next
Play Previous: Media key previous
Mute: Ctrl + Shift + 2
Support for the following features can also be bound to hotkeys by the user (or controlled though the popup):
You can change the hotkeys from the Chrome extension tab. To get there click on : Settings icon (three horizontal lines on top right of browser) => Tools => Extensions => Keyboard shortcuts (link at bottom of page)
If you have any suggestions for more media players to add for the next release let me know! firstname.lastname@example.org
The source code is available here: https://github.com/berrberr/streamkeys.