We've created a new Chrome extension that you might find useful.(maybe) Download it and give it a try!
Download Chrome ExtensionOpen Chrome and go to chrome://extensions/. Enable Developer Mode by toggling the switch in the upper right corner. Click “Load unpacked” and select the extracted folder of the extension. They should extract the ZIP file first if they haven’t already. The extension should now be loaded and available in your Chrome browser.
Click the link below to download the Dislike button Chrome extension for YouTube:
Download YouTube Dislike Extension