Redshift had been deleted from the iso in the past because it did not work. As of 19.03 version it is back on the iso and it includes a fix.
People who stay rolling install it like this
sudo pacman -S redshift
Tip 1 :
Make sure /etc/geoclue/geoclue.conf contains these lines at the bottom (starting from 19.03 it is present)
Tip 2 :
Launch redshift the first time in a terminal. This applies to all users!
You hardly see the effect of redshift in the video if at all.
Check your own systems at daybreak, nightfall and at night.