I need to use YouTube. I have Flash enabled in Chromium's settings, but it always says "could not load shockwave". I am running Lubuntu 13.04
Have you installed
but don't run
unless you really know what you're doing.
Thanks to Erich E. Hoover and his team you can use Pipelight to run Flash, Shockwave, Silverlight and Unity Player in your native Ubuntu browsers.
The steps, reproduced here: