Endpoint: www.youtube.com/youtubei/v1/player
Method: POST

{
    context: ...,

    playbackContext: {
        contentPlaybackContext: {
            signatureTimestamp: "19187",
            referer: "https://www.youtube.com/watch?v=iQfSvIgIs_M"
        }
    },
    videoId: iQfSvIgIs_M
    contentCheckOk: false,
    racyCheckOk: false
}