I am completely with Waterhouse and his comments and I do make an effort to follow the safety briefing. However, I really do switch off when a so-called personality, who means nothing to me, digresses on to something that doesn't mean anything to me. I've become attached to the manual demos, because you can interact with the cabin crew and they, at least on occasion, will interact with the passengers. The manual demos talk about the essentials, stowing hand luggage, seat-belts and life vests. There's no reason for the safety brief to take more than a minute. Whilst I appreciate that at LHR, the taxi to the runway will likely take nearer 20 minutes, there are plenty of airports in thé world where much than a minute will have you hurtling down the runway.
By the way, what are they going to do with safety demos on 3xx planes? There aren't any video screens in those planes anymore.