Hey there! It sounds like you're experiencing some crackling issues with your Bluetooth earbuds while fast forwarding YouTube videos on Firefox for Android. It's great that you've already noticed that this problem doesn't occur on Google Chrome, which gives us a good starting point. To help fix this, you might want to try clearing the cache and cookies in Firefox for Android. Sometimes these files can cause audio glitches. If that doesn't work, you can also try disabling hardware acceleration in the Firefox settings. To do this, go to Settings > General > Performance and uncheck the "Use hardware acceleration when available" option. Give these steps a shot and see if they help resolve the crackling issue.