If I had a part and it had demo of presentation, I'd always make sure there was time for demo and cut back on me talking. Always thought it would be unkind to ask them to get demo together and then not give them a chance to do it. If last minute part and I couldn't find anyone then I'd just do it myself. Same thing with TMS. If someone didn't show for talk I'd ask for volunteers. If no volunteers did it myself or through Q&A with audience. For a long demo (not just a mag or book presentation), I'd make sure people had plenty of notice and a practice session before meeting. Threw in visual aids, humor, etc. whenever possible. Assumed it was a privilege and people should want to do it or at least be given the opportunity. That was before the more recent direction to squeeze even more life out of meetings. Not an elder any more so not an issue for me.