Speak or not, but instructional videos why rely on speech are, IMO, a pain. Unlike a book (or subtitles, or even just a good illustrative video) you can't pause speech and rehear it as you fiddle with something. You can't quick-scan to the bit you need to be unable to rehear, etc. So if you could just make your video good without speech, then adding your voice is surely just icing on the cake - the viewer can mute you if they want, after all.
BTW, using a stand for your camera should be, I think, a far more important concern.