platform/video.videojs/dist/video.es.js
function isPlain(value) {
  return isObject(value) && toString.call(value) === '[object Object]' && value.constructor === Object;
}
function isPlain(value) {
  return isObject(value) && toString.call(value) === '[object Object]' && value.constructor === Object;
}
Returns whether an object appears to be a "plain" object - that is, a
direct instance of `Object`.

@param  {Object} value
@return {Boolean}