So I implemented support last night for a way to filter out modules from a build from a module-set using the KDE Projects database.
To do this before this new feature was implemented, you would have to list each sub module of KDE Multimedia, which means visiting the KDE Projects website, or using some of the developer tools scripts to parse out the KDE Projects database, and then typing that into your .kdesrc‑buildrc. Plus, you’d have to redo this periodically in case a new application or library was added to the KDE Multimedia grouping.
Now, you can simply say that you want all of KDE Multimedia except JuK:
module-set kdemultimedia repository kde-projects use-modules kdemultimedia ignore-modules juk end module-set