Disclaimer: What we call the 'Algorithm' is actually several algorithms each with their own tasks and formulas. The actual name for this is the YouTube Search and Discovery System or SDS (there are several variations of this term but you get the idea). YouTube's SDS is kept under strict lock and key but through analysis and by looking at video performance we get a good idea of how the various components of the SDS works. This article is a simple breakdown of how the SDS works based on what we know about the various algorithms that YouTube uses in order to surface videos to viewers.
It Starts At Upload
Part of the video processing that occurs when you upload a video is YouTube utilizing Google Brain to analyze several components of your video. This process can actually take several hours (days?) and consists of a review of your metadata, your thumbnail, an analysis of the imagery of your thumbnail, the auto-generated captions and even a look at the actual video that was uploaded. This is used to determine several things; what is this video about, is it appropriate for younger viewers, are there any copyright violations and for what category of advertiser is it acceptable. YouTube takes this data and applies a score to your video in order to determine what audience it is appropriate for and what the value of advertising on your video is. Note that a good portion of this does not occur if the video is uploaded as Private, which is why YouTube advises that you switch your video to Unlisted for several hours prior to publishing so that these checks can take place in order to avoid demonitization after it gets published.
Once You Hit Publish...
The fun begins. YouTube immediately sends out a notification to the select viewers who turned on 'All Notifications' and a few of the viewers who selected 'Some Notifications.' If they did not select 'All Notifications' YouTube will only notify viewers if they have been watching your content (or content like what you just published). They don't want to spam every single notification for every single video published. Rather, YouTube wants to provide a pleasant viewing experience for the viewer and is only going to serve them content that they have proven to enjoy and are predicted to enjoy. After notifications are sent out YouTube next sets out to determine the value of your video. They like fresh content and they are always on the hunt for the next new thing. So they begin to share your video in the Home Page Feed, the Browse Feed and the Suggested Videos of similar videos for people who have enjoyed videos similar to what they believe your video is about. Note that this is why it is important to have solid and concise titles, descriptions and tags. It gives YouTube a precise idea of who to put this video in front of.
Tiers of Discoverability
After one hour YouTube moves your video into a different category of discovery. They take the data they have collected and revise the standing of your video. If it did not go viral then it gets put into a holding pattern on Home, Suggested and Browse feeds as YouTube continues to collect data.
Was the immense success of your first hour because you have a large family who all watches your video, but it isn't working for non-subscribed audiences? Did you click on your own video 50 times in an attempt to boost it? Or maybe your video fell flat in the first hour because your current audience isn't into the topic but it is performing really well for outsiders searching the topic? YouTube spends the next 71 hours determining if this video fits the bill as a video that needs to be suggested alongside it's competition. It also experiments with the value of this video in various search queries.
After the first 72 hours YouTube again puts your video in a different category. They are still sharing you out to different audiences, but if the initial audience didn't respond exceptionally well then the impressions will decrease. After 7 days your video is no longer considered 'New,' and YouTube is going to switch gears with discovery. By this time they have a good idea of how long audiences are watching your video not only in general but in the various traffic sources. This is going to put your video in a holding pattern for Search and Discovery. YT will continue to share out your video, though the impressions are going to vary based on how much watch time it ultimately gains when compared to the other videos that YT could be sharing. They will experiment from time to time with different audiences, but ultimately this is where your video is going to sit as the audience which has shown interest has either dried up or moved on to a newer video. Unless...
A Trend Occurs
This actually happens far more often than you'd think. While YouTube values fresh, new content they also value... well value. They want to provide the video that a viewer is looking for when they want it. When a trend comes out of the blue YouTube is ready to pounce, and they are going to kick the tires on old videos in order to capitalize on trending topics. Another thing that is worth noting is that there are more tiers than I mentioned above; for a year I had a strange occurrence of all my videos taking off after 140 days. It happened over a dozen times and it did not matter if I published the video in November or July. 140 days after publishing the video would somehow find it's footing. This is reflexive of something in the SDS that YouTube was doing at the presumed 140 day mark that just happened to work well for the content on my channel. I've seen similar occurrences for videos even years after being published, though the majority of these were the result of videos that were made about a certain topic that for a variety of reasons becomes a trending topic years later.
The Video Dies
I don't mean for this to sound so morose... but at the same time I feel it is worth mentioning. There is only so much audience available for a certain video, and often a hit video can be as much of a curse as it was a success. Imagine getting that hit video which gets hundreds of thousands of views and thousands of subscribers... only to be completely unable to duplicate it's success in future videos. Imagine toiling and working on the verge of what could be full-time YouTuber status as you watch your one hit video decline in views month after month. You kinda need to be prepared for that. Not so much for that sad circumstance, but for the reality that even though you are never farther than one video away from making it you are also going to spend a lifetime recreating it. All videos have a lifespan, and you can not sit back and enjoy one viral hit with the hopes that this was all you need to make it. I have seen many channels with a single viral hit go totally abandoned because the creator got lucky and was never able to redo that success. We here at TubeBuddy have had channels with hundreds of thousands of subscribers ask for help because they can't break one thousand views on a video any more. Part of the value in consistency is the immense library of content that you end up with. This is important because when you have one video go off then your entire library also goes off, but it is also important because you are not as reliant on that single video. It's great when it happens, but it is a soft, warm cushion to have a library of videos each ranking in search to provide the foundation of views (and income) to land on when a viral video comes back own to Earth.
There is obviously a lot of things happening behind the scenes when a video is published and the 'Algorithm' is as much a dark, mysterious thing today as it every was. There will be some things that I missed here, and likely even some things that I simply got wrong. But I hope this at least provides you with some insight into the process that occurs for posting a video, and helps you to better understand how to take advantage of this or at least take some consolation when it doesn't go your way.
