I haven't made any origami Christmas trees but did make a few snowflakes one year. Rebecca Wat has some nice books on fabric origami, which may be available through your guild or at the local library. I often find it easier to open a book, read through the instructions and then work at my own pace to figure out something that complicated. With a video, it may be too many steps to remember, whereas printed instructions will wait patiently for you forever!
