Is this happening on any other On Demand content or just CTV?
The TV digital box may just require a reboot. You can reboot the box by unplugging the power cable for 10 seconds.
If you continue to have issues, please reach out to the technical support department at www.telus.com/chat or 310-6988
After clicking the watch button for any CTV shows I get a loading screen for a couple of seconds then back to the watch button and an error screen. ( An error occurred retrieving the video please try again (10020/6003)
Or is this problem on your phone/tablet? I found using Optik on the Go to be more reliable.