Your system information

• Steam client version (build number or date): Sep 3 2020, 21:18:20
• Distribution (e.g. Ubuntu): openSUSE Tumbleweed
• Opted into Steam client beta?: [Yes/No] No
• Have you checked for system updates?: [Yes/No] Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist

Expected:
Videos in library play in steam.

Actual:
The system default web browser is opened to play videos in library.

Steps for reproducing this issue:

1. Select a video in the library
2. Click on the green play button

Notes:

• For a time the expected behavior was exhibited. Sometime this current year (2020) the behavior changed.
• All other links and youtube videos in feeds open/play in steam.