For video campaigns only
As of May 21, 2018, only a small group of vendors are certified for measurement on YouTube: comScore, DoubleVerify, IAS, MOAT, Nielsen, Kantar, Dynata, and Google (including Google Marketing Platform). Google Ads no longer accepts third-party ad tracking pixels that aren't from these vendors, or that make unapproved fourth-party calls to other vendors.
If you're using pixels from comScore, Nielsen, Kantar, or Dynata, we encourage you to use the Third-party measurement for video campaigns template to request Ads Data Hub (ADH) enablement (with your vendor_client_id included). Please reach out to your measurement vendor for guidance.