Your analysis
might be flawed, due to a recent and unfortunate change of YouTube urls.
It seems that it used to be possible to remove the suggestions by adding
to the end of the url, but that possibility was removed very recently, as stated by
this article.
Perhaps YouTubeStreamFinder used that way of removing them, and now it neither would be able to remove them.
That's why you still get the suggestions when the url looks like this:
https://www.youtube.com/watch?v=dQw4w9WgXcQ&rel=0