Screen time: what does it really mean?

I'm about to have my first and I've been wondering, what does screen time for baby mean?

Seems like a dumb question but here's what I mean: my husband and I watch a lot of movies/YouTube. We like background noise so it's not useually active watching, just something on while we cook or clean. And I can totally see myself catching up on some YouTube once in a while while kiddo breast feeds. But what counts as screen time for baby? Because we don't intend to plop him in front of the TV (especially brand new and against pediatrician advice. We want to be responsible with his tech consumption and follow what his doctor says) but we watch things a lot. We wouldn't be putting something on TV for baby but for ourselves, but does that count as screen time for him?

Just curious. Maybe I'm over thinking it.