We have uploaded a lot of documents to the site through ftp. Some of the documents have flash previews and thumbnails, a lot of documents don't.
It would be nice if there was a way to let the server rebuild all flash previews/thumbnails for all documents through eg a script that could be run manually.
I'm interested by the very same topic (how to make recalculate preview). Additionally, if it was possible to do a request (SQL or LUCENE) to identify all the bad files it would be fabulous. Any answer will be more than welcome.