In the video she doesn't do it from a slip knot. It isn't really necessary but I wanted to see which way I prefer but somehow when I do it with the slip knot, the working yarn ends up at the bottom of the slip knot and the short end is at the top of the cast on (stitches facing right).
With or without a slip knot, I have the 'tail' end over my thumb and the working yarn over my finger. Does that help?
"Place the knot on the needle such that the tail is on the side of the needle nearest you and the working yarn is on the side of the needle farthest from you. The yarn on the far side of the needle has a longer way to travel each stitch and you want this to come from the working yarn so you don't use up the tail faster than anticipated."--found this on line, too.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog