w3af project leader here, while I do agree that old versions of w3af were really buggy and it was almost impossible to finish a scan, the latest versions of the scanner are really stable.
I've been working hard on stability using continuous integration and writing thousands of unittests. At this point each push to the repository triggers +1500 unittests to be run, which test almost every plugin that exists in the framework.
Hopefully this year we'll be able to convince users to come back to the w3af project, since it's better than ever! :)
there are more vulnerable commands. The third result in the search result is a test environment for which the actual project at http://w3af.org/ looks very good. It can also detect more such vulnerability.
I'm on linux so you could try: apt-cache search youtube
(or whatever your package manager commands are) and it'll bring up a list of cli downloaders ;)
if not, you might have to investigate using a browser plugin. I stumbled upon the video last night (while looking for something completely unrelated) and figured it might help someone out. i personally use w3af as it has an owasp top 10 profile already setup amongst other profiles for auditing.