Body
On MAC OS in Safari (versions 11+) there is a feature on by default called Intelligent Tracking Prevention. It causes a cookie error in Safari. Apple has included this as a feature in Safari to protect cross site tracking.
To disable this go to Safari > Settings... > Privacy > Prevent Cross-site tracking and uncheck the box.
Note: This applies to all sites for cross-site tracking which Apple has deemed as a medium risk.
The alternative work-around is to visit https://www.kaltura.com/ before logging into Canvas and that will allow Safari to trust the Kaltura Media player/loader in Canvas. This needs to be done daily as the information is held for only 24 hours in cross-site tracking.