The YouTube API v3 can return the videoCategory of a video. For example, if you make the following request:
www.googleapis.com/youtube/v3/videos?id=ZCJgvabihQ8&key=apiKey&part=snippet,recordingDetails
You will find that the video with id ZCJgvabihQ8 belongs to Category 24. But how can I get the guideCategory id instead of the videoCategory id?
from the Doc
https://developers.google.com/youtube/v3/docs/guideCategories
A guideCategory resource identifies a category that YouTube algorithmically assigns based on a channel's content or other indicators, such as the channel's popularity. The list is similar to video categories, with the difference being that a video's uploader can assign a video category but only YouTube can assign a channel category.
The guideCategory is assigned to a channel, not to a video, and I believe that can be used only to list channels
