I think you are right. I have been out a long time but from what I read here it may be due to the generally poor quality of elders that are becoming the norm. As the internet has become common, possibly many of the better educated JWs are waking up and leaving? At the same time they seem to be having a harder time motivating young men to reach out to be elders. Possibly with wages being not as good as they used to be, even good elders are having to work more to pay the bills so they might not have as much time to prepare talks. Many have said that the overall quality of the meetings are starting to deteriorate.
Maybe they think videos will be more effective in motivating people and making sure they get their message across. If you have a poor speaker you are more likely to not pay attention, while a video has more impact.