You're probably thinking about this video: https://www.youtube.com/watch?v=_wY7FBtr7_c

Leandro submitted it to HN but it didn't get any traction: https://news.ycombinator.com/item?id=25620711

I think this is the first time I'm seeing Felleisen mentioned in the main post. Some comments here mentioned him, but the main post kept his name out.