The video playback issue is a result of either Safari and macOS software needing to be updated. Apple released their newest macOS (16.1 -Ventura) on Oct 24th, so several older macOS versions/Safari versions may experience playback issues. Since Apple may not support automatic updates anymore for those devices, you can try to manually install a Safari update here: https://support.apple.com/en-us/HT204416
If you are unable to install updates with that link, it means Apple no longer supports updates to that device. As an alternative, you can install Chrome or Firefox as your browser to see if you can get the videos to stream, but since your Mac is running an older macOS version, it still may not work.