RPi5 frequently crashes while playing video (rarely while playing audio)

Get a proper power supply (I recommend using the official one) and the issues should be gone.

From the log:

RPi throttled=0x50000
...
Apr 16 23:44:30.671589 LibreELEC kernel: hwmon hwmon0: Undervoltage detected!

so long,

Hias

You have to make sure that the voltage stays well above 4.8V all the time.

If it drops below about 4.65V you'll see the undervoltage errors in the log, but USB devices and other stuff running from +5V may already started to work erratically at voltage above that - the minimum spec for USB and other +5V devices is typically 4.75V min.

See also the power supply section of the official RPi documentation https://www.raspberrypi.com/documentation/…ml#power-supply

Note that the current draw / power consumption is highly dynamic and you'll get issues if the voltage drop lasts for a few milliseconds or shorter. Also note that lots of power supplies don't cope well with those dynamic loads, it's essential that they have very fast regulation.

You have to hook up a scope to +5V/GND at the RPi PCB to check that, using a multimeter is useless as it's way too slow.

so long,

Hias