Easy snell knot......useless!

[Gatorjet]

Tag end through front of the eye, wrap main line (leader 7 or 8 wraps from the eye toward the tag. The video shows a overland knot tied on the end of the tag. After wrapping the main line, insert it through the eye from back to front. Pull tight, and it looks great. UNTIL you give the main line a little slack, and the whole thing starts to unwrap. I've tried it over, and over. I've watched the video over and over. I've looked at the diagram over and over. That is exactly the way I am doing it. Still comes apart when you give the main list new slack. What am I doing wrong?

Here is the video.

https://m.youtube.com/?rdm=1ku7fs6kv&client=mv-google&rdm=1ku7fs6u4#/watch?v=NzM4UxvMXLw