As far as "smushing" too much material on one DVD, in this case it was used to fill up the extra space on the disc, the quality of the material was NOT compromised in any way. It was all presented as originally encoded.
People seem to forget how much material really fits on a single layer DVD. If encoded properly there's usually very little reason to go double layer with a fan project, as an entire film can fit comfortably on one layer if you don't have to go overboard with alternate audio and video. Anything else like extras you just put on another disc.