The guy making the YouTube video is fairly credible. He used to be the head of Collider Video. All that said was it ever confirmed that the Benioff / Weiss trilogy and the Johnson trilogy were actually 2 separate trilogies. I remember when that news broke everyone was treating them like they were, but couldn't just have as easily been they were going to be working on the same trilogy? I could've sworn the actual info was just that each was working on a trilogy, but it never actually stated they were separate trilogies.
I could be wrong though, that news is pretty old at this point.