Hi there! I understand you're having trouble launching the MS NOW LIVE stream on your Windows 10 PC using a WebKit-based browser. To help you better, could you tell me a bit more? For example:

- Are you getting any error messages when you try to start the live stream?
- Is the app installed, or are you accessing it via a browser?
- Have you already tried any steps like logging in, updating the app, or clearing cache?

These details will help me guide you with the most relevant steps. Meanwhile, here are some general troubleshooting tips we can consider for MS NOW live streaming issues on PC:

1. Check Your Login: Live streaming often requires you to be signed in with a valid TV provider or subscription account. Please double-check that you are logged into the MS NOW app or website correctly with an active subscription.

2. Clear Cache and Cookies: If you are using a browser, try clearing your browsing cache and cookies as sometimes corrupted cache can prevent streams from loading.

3. Try a Different Browser: WebKit engines sometimes behave differently. If possible, try streaming from another browser like Microsoft Edge or Google Chrome to see if the issue is browser-specific.

4. Update Your Browser and Windows: Ensure your browser and Windows OS are up to date to avoid compatibility issues.

5. Disable Extensions: Some browser extensions, especially ad blockers or privacy tools, can block video streams. Try disabling them temporarily.

6. Reinstall the MS NOW App: If you are using a dedicated app and not the browser, uninstall and reinstall the app to refresh its components.

7. Check Network Connection: Streaming requires sufficient bandwidth. Verify your internet speed is stable and not restricted by firewall or network policies.

If you could provide any error messages or confirm what you have tried so far, I can help you with more targeted steps. Does any of this already sound familiar or worth trying?