Cannot play videos in my iPad Air after upgrading to iOS 8.0.2
After posting this same question in Apple Support Communities Diavonex quickly replied with a simple solution:


  (A) Try reset iPad
  
  Hold the Sleep/Wake and Home button down together until you see the Apple Logo.
  
  Note: Data will not be affected.
  
  (B) Close all apps in the multi-task window
  
  1.Double-click the Home button.
  
  
  Swipe the app's preview up to close it.
  Preview will fly off the screen.
  


Reference: https://discussions.apple.com/message/26841501#26841501