Any reason not to export it? If I want to tweak playbin's flags I usually have to define this enum in the client code.

typedef enum {                                                                                                                                                                                                       
  GST_PLAY_FLAG_VIDEO             = (1 << 0), 
  GST_PLAY_FLAG_AUDIO             = (1 << 1), 
  GST_PLAY_FLAG_TEXT              = (1 << 2), 
  GST_PLAY_FLAG_VIS               = (1 << 3), 
  GST_PLAY_FLAG_SOFT_VOLUME       = (1 << 4), 
  GST_PLAY_FLAG_NATIVE_AUDIO      = (1 << 5), 
  GST_PLAY_FLAG_NATIVE_VIDEO      = (1 << 6), 
  GST_PLAY_FLAG_DOWNLOAD          = (1 << 7), 
  GST_PLAY_FLAG_BUFFERING         = (1 << 8), 
  GST_PLAY_FLAG_DEINTERLACE       = (1 << 9), 
  GST_PLAY_FLAG_SOFT_COLORBALANCE = (1 << 10),
  GST_PLAY_FLAG_FORCE_FILTERS     = (1 << 11),
} GstPlayFlags;