Good to hear you enjoy your MorphOS experience!

1. Watching videos is CPU intensive work, because we don't have software/drivers for hardware decoding of videos. Only hardware assistance is the overlay option, which can scale videos with no extra cost, but decoding itself is done by the CPU still. By default YouTube doesn't use the overlay playback and maxes out the CPU load, but there's a script for OWB that makes those videos run in a "full window" overlay mode. With the script CPU load of YouTube playback drops from 100% to somewhere around 30-50% on a Mac mini 1.5GHz, and that makes the fan speed much slower too.

By the recent changes in YouTube, we now have to spoof OWB as iPad if we want to browse the actual UI on YouTube, and that also needs an updated "Fullscreen Fix" script. More info here: https://morph.zone/modules/newbb_plus/viewtopic.php?forum=9&topic_id=12903&post_id=146399&viewmode=flat&sortorder=0&showonepost=1

And games are CPU intensive too. You can enable the CPU Monitor screenbar module to see when the CPU is under heavy load. In normal use the fan speed stays quite moderate, even when browsing, because CPU load isn't constant then. But for games, non-overlayed mid-resolution videos, or HD videos it will stay at max and makes the fan noisy too.