Here’s a datapoint. Running Librem 15v3 with an up-to-date PureOS green (installed from the Calameres ISO) with no post-install power configuration that I’m aware of:
~> cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
powersave
powersave
powersave
powersave
~> cpufreq-info | grep 'current CPU fr' # no videos running
current CPU frequency is 500 MHz.
current CPU frequency is 488 MHz.
current CPU frequency is 500 MHz.
current CPU frequency is 500 MHz.
Just ran 5 background videos in MPV for ~1 hour with no issues. I have previously had occasional system freeze-ups (forced to hard reboot) while interacting with PureBrowser (and no video running) – I assumed it was a PureBrowser issue that will be resolved when it’s next synched with Firefox.