I would like to see this implemented. Currently movie/TV/Video playlists show a jumbled collection of poster art for the films/shows/Videos that are part of the list. I would like to be able to update the poster art, and adding a collection tag would be a bonus.
An example: I have a Walking Dead auto-playlist of my unwatched episodes of “Walking Dead”, “Talking Dead” and “Fear The Walking Dead” sorted by air date. It would be nice to give that playlist a custom poster, and a “Walking Dead” tag so that when looking at “Fear The Walking Dead” in my library, it would also show the playlist available for the whole series.
It’s a little thing, but the little things tie everything together. 
Mod-Edit:
focused the post to avoid overlapping with the existing/popular suggestion asking to support custom posters for playlists (see post below)
