Fix: new video embed for news-use (#3083)

- Video embed alternative
- Demo from media repo

    
<!-- This is an auto-generated description by cubic. -->
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## Summary by cubic
Switches the news-use demo video embed to the hosted media repo for
reliable playback and faster loading in docs. This replaces the GitHub
user-attachment link that could fail to load.

<!-- End of auto-generated description by cubic. -->

Author: avocardio

docs/examples/apps/news-use.mdx

@@ -12,7 +12,7 @@ This demo requires browser-use v0.7.7+.
 <video
   controls
   className="w-full aspect-video rounded-xl"
-  src="https://github.com/user-attachments/assets/698757ca-8827-41f3-98e5-c235d6eef69f">
+  src="https://browser-use.github.io/media/demos/news_use.mp4">
 </video>
 
 ## Features