The Blizzard Battle.net desktop app requires a specific version of Adobe Flash to play videos in the app. To install the correct Flash plug-in for Windows:

  1. Visit the Adobe Flash Player download page.
  2. Select your operating system from the first dropdown menu.
  3. In the second dropdown, select the option for Firefox (NPAPI).
  4. Once the update is complete, restart the Blizzard Battle.net desktop app.