I don't think the current video format is very good for retention. Putting it in the form of a quiz could help frequent travelers actually memorize the information over time, which could in turn save lives.
There’s also the argument that to improve retention, the regulatory body should decrease the amount of “key safety messages” that need to be included in the videos (which ends up being around 35-45). If you decrease that number, retention of the info you do mention should go up.
I would expect it's at least slightly better for morale, recruiting, and retention. I also expect that executives and middle managers move to use these as an opportunity to reinforce corporate values, whatever that means to them.
It reinforces the brand. Virgin gets to show it's sexy. ANA that it's fun but sophisticated. United that it has four neurons firing across the enterprise.