I do the same on my forum, but manually, with an external php script and an include in the header.
Not too long to do (the longer is to do the thumbnail, which solution you choose), the only problem is that i'm the only one who can do it (I must upload the the server FTP, edit the external php file...)
http://www.eovia3d.net if you want to take a look
But i'll be glad to find a mod/plugin which do that more easily