I have never been able to second screen, I just can't focus on my PC while listening to something. It's literally white noise to me. I do understand people do this though. When I do watch media seriously, I pay attention and keep off my devices.
Yeah my attention during second screening is split such that I'm now doing two things _terribly_ instead of one thing well. I've decided to only have music or something equally non intrusive in the background instead of second screening a show/video/podcast.
I use music too but it can't have too many vocals. I will start to pay attention and get distracted. Similar to how I can't fall asleep with a TV on, I'm still going to listen to it.