Somehow I made you think that I'm sitting idly waiting for my computer to finish encoding one clip before starting the next download, and that I am not familiar with the concepts of batch-processing etc. ;)
What I was trying to say in my original posting was that the whole process of getting a course ready for a mobile device is a lot of trouble for the individual, whereas it would be a piece of cake for the site administrators.
Getting a course ready for offline viewing involves going through the whole course ("next", "next", "next", "next", ...), clicking on "download this video" on every page, waiting for the download to finish (at least my experience seems to indicate that the download-server does not process simultaneous requests from the same client, if I already have a download running, a new download does not start until the current one is finished), and finally encoding the downloaded clip. The clips can of course all be encoded in one go, but as outlined above, that is just one step among many inconvenient steps, and I guess since the downloading is the real bottleneck, I'll already be done encoding the videos I already have before the next ones arrive, so batch-encoding isn't a great help here.
Looking at it this way, I guess it would already help having a "download all videos for this course"-link, so one could get the whole course in one go and then indeed batch-convert them.