I had this problem with HDR content from the TV app, so it's not just YouTube. @jclo I read through the error message on reboot and it actually said there was a power draw issue, funnily enough my crash happened right after a transition to a bright scene in a movie... like the system couldn't sustain enough juice for that HDR light burst.
My system was fully charged, plugged into the 140W adapter, and a thunderbolt dock.
My system was fully charged, plugged into the 140W adapter, and a thunderbolt dock.