It works, if you select it before making your post, but only in the forums in which it is enabled.
I noticed the test forum does not have HTML enabled. Should it be for a test forum?
In a forum with html enabled, I couldn't see that it worked. Of course, I'm not sure how it works. I used things like <b> rather than [b]. Maybe it doesn't show in the preview but does after posted?
Mainly, I wanted to use something for text indenting rather than using the [quote] markup. I had thought of using inline CSS styles if not using <blockquote> or <dl>.