The following documentation says it’s not required:https://dev.twitter.com/docs/cards/types/player-card
The validator says it is “required” when you mouseover the field: https://dev.twitter.com/docs/cards/validation/validator
The validator’s mouseover text is worded as if it is optional: " If provided, the stream must be delivered in the MPEG-4 container format (the .mp4 extension)."
Can you please clarify this issue? It’s frustrating that you would change the required fields from under us