“Fatal error: Call to undefined method WPDM_CategoryHandle…” the error only may happen if all files not uploaded properly, please delete current installation and reupload latest version.
wpdm-categories short-code will show only categories, not the packages. For showing package under categories, you need to use category short-code. I added some sample in that page, please check http://vocaloid.de/downloads/ .
In fact, the query they mentioned is a simple wp query with a search phrase, nothing to optimize there at all. But please update download manager asap, we have fixed some security issue there.
it was showing login form as you select hide everything option, anyhow I also change the code to show the login message even for that option, showing ok in your site now. However I also updated code in my side to show login message for hide everything option.
@NSpehler, actually it is not an issue with wpdm, if other plugin/theme using same variable name they can also change it, however we have scheduled to change it for next update.
