Doesn't seem new to me
I remember going to lectures on this some years ago.
Perhaps it's bad translation but his statement should read:
"The existence of free-floating planets has been predicted by planetary formation theory, but nobody knows how many there are."
because we still don't know how many there are, he only spotted a few. The hunt for "dark matter" is still on and according to some lectures I went to the lack of "dark matter" has lead to the theory predicting it being questioned.