No, they only work in a template. ETA: Well, yes, they'll work in <script> tags if it's in a template.
It looks to me like you want to put your code in a template and use it as part of an existing vbulletin page, or else write your own page using the instructions at the link posted above.
I'm not so sure what happen, but I think there were to many {vbulletin} tags in that var source = "____.php" code, so I shortened it to one and it worked flawlessly.
But one thing I noticed, is it normal that if you try to post the same content twice in vBulletin 4.1.10 the second one doesn't post?