I prefer written instructions (which almost always have pictures). Every once in a while I'll want to see something specific and will find a video on it, but I usually find the particular part of the video rather than watching the whole thing.
My problem with videos is that it's hard to figure out if they're worth watching without actually watching them, and they're often very long. Long is fine if they're covering a lot of ground, but often most of the video is spent chatting or showing things that really don't need to be shown (if the video is not about how to cut things out with a scissors, then I don't think it should show the person cutting things out with a scissors, IMHO). With written instructions I can more easily skim through them and skip the parts I'm not interested in.
Just the other day I found a video on something I wanted to see, and it included how to thread the needle (hand sewing) and how to tie a knot in the end of the thread. It must have been intended for someone who had never sewn before, but that makes it tedious if you have. By the time it got to the part I wanted to see I was seven or eight minutes in (which admittedly only took two or three minutes of my time to find).