You don’t create a reference for an asset directly using the <reference> tag. You create the reference indirectly by defining a relationship between the asset and a file that contains the audio or video content you want Content ID to use for matching, or a fingerprint of that content (that is, a <file> whose type attribute is video, audio or x-gfp).
<file type="video"> <filename>foo.mpg</filename> </file> <relationship> <item path="/feed/file"/> <related_item path="/external/asset[@id='ASSET_ID_1_']"/> </relationship>
You can also create a reference by defining a relationship between the asset and an existing YouTube video, as long as the video was uploaded to a YouTube user account that is linked to your content owner.
<relationship> <item path="/external/video[@id='VIDEO_ID_1_']"/> <related_item path="/external/asset[@id='ASSET_ID_1_']"/> </relationship>
When you create a reference, YouTube returns a unique reference ID in the status report that details the actions taken while processing the feed. You use the reference ID (and the <reference> tag) to delete, deactivate, or reactivate the reference.
When you create a reference for an asset, you must also specify a match policy for the asset.