I'm preeeeeeeeeety sure the only thing you'd see is my face getting increasingly red as I vibrate and grunt occasionally...
I have a firewall on my phone, I don't let it talk to 1e100.net (google) or facebook or amazonaws (have to allow this sometimes unfortunately since everything uses it) or a few others. It's a bit of a pain in the bum and I honestly don't know if it does anything really, but I see all the thousands of constant attempts to connect to these servers so I guess it's at least probably stopping a bunch of this sort of low-level spying?
What're the hackers or government going to do with hours of footage of my disgruntled face at a bad angle? I guess facial recognition but I doubt they'd need it. Voyeurs, go for it man.
how do you know they haven't already? the firmware isn't opensource afaik.