Hello! I understand you're experiencing an issue where preview videos on the American Greetings Ecards app stay black and don't play properly. Let's look into it together.

To better assist, could you tell me:
- Are you using the American Greetings Ecards app or the website in your WebKit browser on Windows 10?
- When did this problem start? Was it after a Windows update or app update?
- Have you tried any fixes already, like restarting the app, clearing cache, or reinstalling?
- Does this happen with all videos or just certain ones?

Meanwhile, here are some straightforward steps to try that often fix such video playback issues:

1. Refresh and Retry: Simply reload the webpage or restart the app to see if the video loads properly after a fresh start.

2. Clear Cache:
- Since you are on Windows 10 with a WebKit browser, clear your browser cache.
- For WebKit-based browsers like Safari or others, you can usually clear browsing data from settings > privacy or history.

3. Check Network Connection: Make sure your internet connection is stable. Sometimes slow or spotty connections lead to videos not loading.

4. Allow Site Permissions: Verify your browser allows media playback and that any ad-blockers or privacy extensions are not blocking video content.

5. Update Software: Ensure your browser and Windows 10 are up to date. Compatibility problems can cause playback issues.

If you are using the American Greetings app itself (rather than a browser), consider:

- Going to Settings > Apps > American Greetings on Windows, then selecting Advanced options and choosing Reset to clear any app-specific cache.
- If that doesn't help, uninstalling and reinstalling the app can refresh corrupted files affecting video playback.

If you’ve already tried some of these, please let me know which ones so I can look into more advanced solutions.

Are you able to share the answers to my earlier questions? That will help me narrow down the cause!