Youtube API v3 enables developers to retrieve specific information regarding a particular video, among the returned data a part called topicDetails can be requested as per the following example:
Request:
https://www.googleapis.com/youtube/v3/videos?id=7lCDEYXw3mM&part=snippet,topicDetails
Response:
{
"kind": "youtube#videoListResponse",
"etag": "\"r3ahjFekUqNiL0By9B5wQ2uTZHM/i4Bt9XfY8YZ1ctSlg8BWcLD8HFQ\"",
"items": [
{
"id": "7lCDEYXw3mM",
"kind": "youtube#video",
"etag": "\"r3ahjFekUqNiL0By9B5wQ2uTZHM/hYUGsnkhqATV4OXNG43HIObqlyw\"",
"snippet": {
"title": "Google I/O 101: Q&A On Using Google APIs",
[ some properties have been omitted here ],
"categoryId": "28"
},
"topicDetails": {
"topicIds": [
"/m/045c7b",
"/m/0z5n",
"/m/04136kj"
]
}
}
]
}
The topicIds field comes machine encoded and topic information can be retrieved through the Freebase API (using this identifiers) which is being deprecated. I was unable to locate any update on YouTube documentation regarding the impact of freebase API deprecation and as I manage a large node.js code base that relies heavily on YouTube topicDetails I would like to ask if there is any known programatic alternative to recover topic information from stable sources other than Freebase?
As part of the Freebase retirement announcement, Google said that they would be offering a couple of new Knowledge Graph APIs and that there would be a 3 month overlap between the availability of these new services and the shutdown of Freebase.
Presumably Google services like YouTube which depend on Freebase MIDs will transition to these new services will transition to the new API (perhaps with unchanged identifiers), but not much is known concretely because a) Google is overdue with the new APIs and b) they haven't said anything else about the transition process.
UPDATE: The Google Knowledge Graph Search API became available in December 2015 and provides support for looking things up by KG ID (which is the same as the old Freebase ID used by YouTube).