The comment implies that this is somehow hardcoded just for Google sites, which is not true. Autoplay is allowed for sites with a high enough media engagement index. You can check chrome://media-engagement.
The preloaded list is in the source code (https://github.com/chromium/chromium/blob/master/chrome/brow...) but it's encoded as a finite state automaton that makes it a bit difficult to enumerate the list of whitelisted domains.
The preimage space is finite and easily enumerated.
[0] https://github.com/chromium/chromium/blob/615d5eed47c10d8890...
https://www.chromium.org/audio-video/autoplay/autoplay-pre-s...
According to the MEI it actively measures user behavior and one of the most important measures is that a video is unmuted. From the document:
“The MEI is meant to allow media heavy websites (e.g. YouTube, Netflix) that rely on autoplay for their core experience. It is a non-goal to allow websites with a “good media behaviour” to autoplay without restrictions”
It doesn’t sound too good, and still doesn’t really explain how everything is seeded.
Here is the code: https://gist.github.com/NeatMonster/e9cdb01441a3cd842e6a20fd...
And here is the plain-text list: https://gist.github.com/NeatMonster/e9cdb01441a3cd842e6a20fd...
These are the kind of tricks a shady company would do. So disappointed what Google is doing to the web the last few years.
It isn't obvious to me from this that Google are privileging their own sites above others here