JsonParser.swift

  var videoSources: [CtsVideoSource] {
    var sources = [CtsVideoSource]()
    for lv in left {
      // for each left video
      if let source = lv.videoSource {
        sources.append(source)
      }
    }

    for rv in right {
      // for each right video
      if let source = rv.videoSource {
        sources.append(source)
      }
    }
  } // videoSources