curl --request PATCH \
  --url https://api.tella.com/v1/videos/{id}/clips/{clipId}/blurs/{maskId} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "durationMs": 123,
  "startTimeMs": 4503599627370495
}
'

{
  "mask": {
    "dimensions": {
      "heightPct": 50,
      "widthPct": 50
    },
    "durationMs": 2000,
    "id": "ly_abc123",
    "point": {
      "xPct": 25,
      "yPct": 25
    },
    "startTimeMs": 1000,
    "type": "blur"
  }
}