I’m trying to find the video that helped me. The key to opening up that loop was that the throw hand does a circle around the yoyo and then pulls the string to the right. That makes the loop open up. But it’s completely a “feel” thing. If you overdo it then it won’t work. But when it does work try to remember how that felt and try to duplicate those motions.
If I can find the video again I’ll post it here.
EDIT
Found It!
Notice how his throw hand is moving to the right and up? That’s opening up the loop.