I am customising the mediawiki for our internal portal.
I need to open a popup window on clicking a link in the wikitext. This popup would take information from the mysql database and display a movie clip or a document or something.
Anyone knows how this can be done?
You've probably considered this but just to be sure - many people really hate popups which is why modern browsers have pop up blockers. So, if you use them, you'll have to include browser specific instructions on how to enable pop ups.
As an alterative, I suggest you embed the movie clip / document - using e.g. an iFrame.