Twitter Card validator doesn't render my 'player' card properly


Hello, I have added support for video Twitter Cards on MediaCrush, but the Twitter Card validator doesn’t let me play the video (in fact, it doesn’t even attempt to iframe my player). It does show the thumbnail I provide, though.

Here is an example of content shared through MediaCrush that would contain a Twitter Card:

The validator says everything is fine, but it doesn’t actually work. Am I doing something wrong, or is it just the validator being silly?