In 1975, the French philosopher Roland Barthes wrote that his favorite part of going to the movies was leaving. But then Barthes was never locked out of cinema by a global pandemic. I’m a film professor, which means I spend a lot of time watching movies at home, even under ordinary circumstances. In my most recent book, “The Stuff of Spectatorship,” I investigate the ways we watch movies now, especially at home, but I also love cinema: The darkness, seclusion and surround sound create an immersive experience I can never replicate in my living room. And then, of course, there’s the popcorn. That may have been what I missed most.