Nokia Lumia 920 - I can share pictures with Lumia Play to but why do my videos not play on my TV or Blu-ray player?

Please check the user manual of your TV or Blu-ray player to ensure that your device supports the video format that you are trying to share with the Lumia Play to app. The Lumia Play to app is responsible for sharing the content from your phone to the TV or Blu-ray player, but it is up to the TV or Blu-ray player to play the content.