A frame that displays a series of videos to preview, without collecting data as a live experiment. User can go through these at their own pace and video controls are shown. Webcam video is recorded starting once the user presses a button to actually display the videos, so that researchers can check that the participant (infant/child) did not see the videos ahead of time.

"frames": {
   "my-sample-frame": {
       "id": "video-preview",
       "kind": "exp-video-preview",
       "text": "Here are the videos your child will see in this study. You can watch them ahead of time--please just don't show your child yet!",
       "prompt": "My child can NOT see the screen. Start the preview!",
       "videos": [
          {
            "caption": "User-facing text that appears below the video",
            "sources": [
              {
                "type": "video/webm",
                "src": "https://url.com/example_intro.webm"
              },
              {
                "type": "video/mp4",
                "src": "https://url.com/example_intro.webm"
              }
            ]
          }
        ]
   }