Note the challenge here with the way that DS is setup.
1) Image - would have to play for the exact time - not much of an issue
2) Video - if it was a different play time -- then there would be a gap or a blank space in the timeline
Some providers don't work on playlists, but instead a content list. The latter works because in general, people don't want blank spaces.
With the timeline system, there is potential for overlap and blanks -- although I don't see those being the majority of users ideal situations.
running from a folder provides a lot of variety and flexibility for random, inserting, replacing, etc. But that's not how this works.