Man tests to see if Google is listening through microphone, result is surprising

That first click on the dog toy ad likely caused all other tabs to show related and/or exactly this ad.

It doesn’t explain first ad though, but we know nothing about his setup - what phones and other devices he has and what software is currently activated on them.

I don't see this as conclusive at all. I tried it out on my macbook air in chrome and did not get any ads for the item I talked about.