With the release of Vivaldi 2.2, this page is now obsolete and unmaintained. Widevine is fetched automatically on post install of our official packages. The information below and the script are left for historical reasons but will not be updated.
A bunch of people asked how they could use this script with pure Chromium on Ubuntu. The following is a quick guide. Though I still suggest you at least try Vivaldi. Who knows, you might like it. Worried about proprietary componants? Remember that libwidevinecdm.so is a binary blob you are taking from Chrome, so by following this guide you will have already made your distro less "pure". Also all our additions to the Chromium base are open source and our UI, while not open, is written in HTML/CSS/JS. Thus you can see exactly what we are doing (no funny business).
If you still want to run Chromium, the following explains how it is done.