When using VLC, why does my screen saver keep waking up?

XScreenSaver uses DPMS to turn my laptop screen off. I'd like to find out why it's waking up to the prompt again. I enabled logging with log, but it shows nothing useful, > xscreensaver: 22:04:21: logging to "/tmp/f" at Thu Apr 26 22:04:21 2018 That's all that's in the log. Checking /var/log/kern.log, I see > xscreensaver: pam_ecryptfs: seteuid error How can I debug this issue, what are the likely causes of XScreenSaver waking my display up. I'm using xscreensaver 5.36.