I think the post is saying the ads would be burned into the regular video stream such that even offline downloaders such as youtube-dl would also get the ads.
The current common behavior is the actual video and the ads videos are 2 different streams. The javascript in the web browser switches back & forth between the streams for dynamic ads insertion as it gets the next media fragment(s). The new behavior is to have just one indistinguishable stream that's more tightly embedded into the video media fragments.
If the above paragraph doesn't make sense, one can just load up a Youtube video while monitoring the "Network" tab in F12 Developer Tools to see the various media fragments being downloaded while it switches between the normal video and the ads.
“Love, friendship and respect do not unite men as much as a common hatred for something.”
That said, the predictable next step would just be for Google to turn on DRM on Youtube videos.
I might click on a video I find elsewhere, but I’ve basically given up on using the YouTube interface for finding videos.
Not just you, youtube has as well.