Mini-hack: how do you stop xscreensaver from kicking in, if you're watching youtube videos? Well, how I do it is this:
"crontab -e" in a terminal to edit your personal cron file, and add this line (it's all one line) to it:
*/2 * * * * XDG_RUNTIME_DIR=/run/user/1000 bash /home/aquarius/bin/xscreensaver-chrome-suppress.sh
then create /home/aquarius/bin/xscreensaver-chrome-suppress.sh (obviously, change the path to put this somewhere you want it to go), and put this in it:
if pacmd list-sink-inputs | egrep 'application.name
= "(Chrome|Chromium)"'; then
and you're done. I imagine that this can be generalised to work with Firefox or other browsers as well. It's obviously a bit sus, because it will also suppress the screensaver if you're just playing audio
in a browser tab, but I'm fine with that.