The difference between these is the compression level that will be applied, a bit like the play modes on a set-top DVD recorder or VCR. For example, the DVD High quality applies the least amount of compression. Lower compression gives better picture quality, but with the drawback of giving less recording time. Higher compression gives more recording time, but at the cost of picture quality.
The best one to choose is the one that is nearest your AVI length (in minutes) without going under. For example, if your AVI is 70 minutes, choose the “Good Quality 90 minute” profile.
The DVD DL time refers to Dual-layer (8.5GB) discs, which provide nearly double the recording capacity over regular recordable DVDs.