Good points Heleen. Providing handouts or worksheets or tasks to students allows them to continue learning in case you are temporarily offline. So while the "plenty to read" was said in jest, if it was useful support material, then it is good.
Conference presentations are one thing, and we can't be upset if learners only pay half attention, but if this is a course for which students expect a certificate, I don't think our expectations for attention should be less than in a classroom. (Shame on you for listening with half an ear :) Maybe there should be some agreed upon limitation for periods for unexpected downtime. If longer than 10 minutes, the session is cancelled and the content is recorded and exercises packaged for asychronous use, or postponed if possible.
Yes, I would expect the trainer to be engaging, asking me questions frequently, giving me exercises to do, and telling me things that he has convinced me will be useful to learn. If he uses well designed visuals, and not so much text to accompany the talk, and talks to ME and the other learners rather than his expert colleagues, then my attention will stay at a high level.
This list will get long with the contributions of others, I'm sure...
Pat