Hi everyone,

I’m curious about how YouTube’s offline video functionality works in web browsers. Here’s what I’ve observed and would love to get some technical insights from the community.

Recently, I downloaded a video from YouTube using the web version. The video is quite long—about 3 hours—and I was able to watch it offline without any issues once it was downloaded. What puzzles me is that despite the video’s large size, the browser’s cache and storage didn’t show a significant increase in size.

Web browsers typically have storage limits for offline data such as cookies, cache, and local storage, often ranging around 5 MB for these purposes. Given this limit, I’m wondering how YouTube manages to allow such large video downloads and playback in a browser. I’ve tested this across different browsers, and it works perfectly.

Some technical points I’m interested in:

1. How does YouTube circumvent browser storage limits to enable large video downloads? Is it using some form of server-side storage or special techniques?

2. What mechanisms are in place to manage and retrieve these offline videos without significantly affecting local storage?

3. Are there any JavaScript or web API methods YouTube employs to handle this efficiently?

I would really appreciate any technical explanations or insights into how this works.

Disclaimer: I don’t have YouTube Premium. I’ve noticed that in my current country (where YouTube is automatically set to a local version), I’m able to download videos and watch them offline without ads. This could be due to the fact that there are fewer advertisers here, and many people don’t speak English or use Latin script.

Thanks in advance for your help!