Buffer health, which is in the “Stats for Nerds” dialog when you right-click on a Youtube video, tells you how many seconds the video can continue playing before it has to download more of the video. This time starts at the current time in the video.
When you watch a Youtube video, Youtube keeps a buffer in its memory and downloads several seconds of the video in advance, before your browser even plays it. That’s why you sometimes see a white horizontal bar moving forward at the bottom.
Youtube keeps an in-memory buffer health so that it does not have to pause the video to download more of it and display that annoying rotating circle that appears when Youtube has to download more of the video.
Why is my Youtube buffer health very low?
On faster connections, Youtube will use a smaller buffer health since it can download the video quickly. This saves memory, especially on mobile phones and tablets. But on slower connections, Youtube is forced to use a larger buffer.
If the buffer health is too small, then the video will repeatedly interrupt to load more of itself, which makes a poor user experience, and the user will either try playing another video or exit Youtube entirely. So the buffer health is very beneficial for Youtube’s profit, and also for viewers.
Here’s a great writeup about buffer health on Reddit by user u/YYqs0C6oFH:
The buffer health tells you how much video buffer it currently has downloaded waiting to be played. If you have plenty of available bandwidth, it can get away with using a smaller buffer since it can quickly download more as needed. While the network activity is 0, the buffer health will go down 1 second per second as the video plays, and when the buffer gets low, it’ll try to download the next chunk to refill it (you can see the buffer health graph jump whenever the network activity spikes). A buffer of 20-30s is probably fine with the available bandwidth you have.A little help understanding YouTube tv stats for nerds – Reddit
If Youtube videos are not loading for you:
- Make sure your connection strength is good and you are not too far away from your WiFi hotspot.
- If you are on 2G or 3G or LTE, then sometimes, some carriers have signal reception issues, so simply wait.
- Ensure you are not downloading or streaming too many items at once because this also prevents Youtube videos from loading.
- As a last-ditch resort, notify the Youtube support team or their Twitter account about the problem. In rare cases, Youtube has outages in some regions.