I wouldn't consider looking at your phone while watching a movie "multi-tasking." Simply doing one thing when you're "supposed" to be doing something else isn't multi-tasking. Multi-tasking is doing and paying attention to muliple things at once. For example: I work at a marijuana dispensary, and a lot of our downtime is spent rolling joints. I always listen to an audio book or podcast while I'm rolling, and I can easily focus on both tasks. No one is going to convince me that that isn't more productive use of my time.

I have a severely limited time on this earth: not nearly enough to consume and learn everything I want to. 🤷‍♂️