Sloped BO?

I am making a camisole. I am trying to avoid the stairstep in binding off. I found the sloped BO; however the video and directions contradict each other.
the written directions say " Slip the first stitch from left needle p-wise. Pass the unworked stitch over the slipped stitc"

But the video shows that once she turned the work she slipped the stitch Knitwise, instead of purlwise.

Which is the correct way, and if I am binding off on a purl row, which way do I slip the first stitch on the left needle?

Thanks for any help

There is an excellent explanation here, with photos: