Packaging decides the click
On YouTube the thumbnail and title are the advert for the video, seen long before a frame plays. A 16:9 thumbnail, which YouTube recommends uploading at 3840x2160, has to read on a phone held at arm's length and on a television across the room, so it wants one subject, strong contrast and few words. Titles can run to 100 characters, but lists cut them short, so the point belongs at the front. A/B testing in YouTube Studio lets a channel try up to three titles, thumbnails or both on one video and picks the winner on watch time. Generate genuinely different concepts to test, and never promise what the video does not deliver: maliciously misleading thumbnails breach YouTube's spam policy.
Chapters, descriptions and search
YouTube is a search engine, and a description of up to 5,000 characters is where a video explains itself to it; only the opening lines show before the viewer expands it. Chapters do double duty. They let viewers jump to the part they came for, and Google can show them as key moments in its own results. The rules are strict: the first timestamp must be 0:00, there must be at least three in ascending order, and each chapter must last ten seconds or more. Drafting descriptions and chapter lists from the edit's transcript is quick work for AI, but a person should check every timestamp against the final cut.
Captions, subtitles and dubbed tracks
Automatic captions misspell brand names, product names and technical terms, so upload a checked caption file for every video. Subtitles open a video to other languages; dubbed audio goes further. Multi-language audio, open to channels with access to YouTube's advanced features, lets one video carry several language tracks under one URL, keeping views and comments together instead of spreading them across regional channels. The studio voices and dubs into 30 languages with timing preserved, and localises subtitles with terminology and approved claims enforced, so the Spanish track says what legal signed off in English.
Series, and synthetic content rules
Channels grow on series: a recurring format with a fixed structure, look and cast that viewers come back for. That suits AI production well, because saved sets, characters and styles keep episode twelve looking like episode one. Two rules to plan around. YouTube requires creators to disclose realistic altered or synthetic content, such as a generated person or a real event that did not happen, through a setting at upload; animation, colour correction and AI-drafted scripts do not need it. And a square or vertical upload of three minutes or less is treated as a Short, so long-form cut-downs should be exported at 16:9.
Updated 25 September 2026