Universal Media Server | Forum

How can i config UMS to only list video files in a given folder (or all sub dirs) or only pictures or only music?

You can't if you browse by folder (as far as I know). But, if you use the media library/cache the files are already divided into video, audio and images. The is however a fork of UMS called UMS-MLX where you can do a lot of customization to the media library. There you can probably achieve what you want.