Does anyone know of a video showing how to p2togtbl. I can do k2togtbl, but I am having trouble with the purl ihrough the back loop. thanks

It’s tricky, another and easier way of doing it that doesn’t have twisted sts on the knit side is ssp - slip both sts separately knitwise, then knit tbl.

I don’t know of a video but here is what I do… with the yarn in front as if to purl rotate the work so that I’m looking at the back side. Now insert the RHN into the second stitch from the needle tip moving from right to left and on through the first stitch as well. Now rotate the work back so that I’m looking at the front again, and finish purling the 2 together, just like I would finish purling if it was only one stitch, IOW yarn around and pull up my new loop.