ExtensionFM is arguably one of the coolest extensions you can find for Google Chrome -- it's a must-have for music lovers. But if you're browsing with Chromium or a Chromium-based browser, you may have noticed that you can't listen to MP3 files in it. What gives?!

Alas, this is one of the differences between the open source Chromium browser and its semi-closed brother, Google Chrome. Many of the audio and video codecs included in Chrome aren't included in Chromium due to licensing, patents -- all that fun stuff.

Fortunately, there's a workaround -- and it's pretty dang simple. All you have to do is copy over the official Google Chrome audio/video components and paste them into your Chromium browser's folder.

Let's go!
If you don't have both Chrome and Chromium installed, you'll need them. Grab a dev channel version of Chrome if you need to, as it's the closest thing to a Chromium snapshot build.

Windows

You're looking for three files: avcodec-52.dll, avformat-52.dll, and avutil-50.dll. They'll be located in your Chrome\Application folder (somewhere like C:\Users\You\AppData\Local\Google\Chrome\Application.0.437.3).
You can get to them pretty quickly by going to start > run > %localappdata% [enter] and then drilling down.

Linux

I'm running Ubuntu, so your folder locations may differ depending on your distro of choice. The file you're after is libffmpegsumo.so and it's located in /opt/google/chrome on Ubuntu.