YouTube embeds failing

I unable to add videos because of a 403 error. The error I can see in the network tab of the browser is:

{
  "error": {
    "code": 403,
    "message": "The request cannot be completed because you have exceeded your quota.",
    "errors": [
      {
        "message": "The request cannot be completed because you have exceeded your quota.",
        "domain": "youtube.quota",
        "reason": "quotaExceeded"
      }
    ]
  }
}