Okay, here is a tremolo. I attempted to use my usual picking method. (I tried to "encourage" this by warming up with playing the major scale as fast as possible before. I could upload this as well, if you are interested, but it looks somewhat like string-hopping to me, although when I played it back, it was faster than I expected/ remembered.). So I think it looks most like wrist motion (although potentially with tremolo I might feel like treating it as a special case and use elbow motion although that might not be my usual picking technique). Anyway, with the tremolo, I did a couple of previous takes which were crisper; but a bit jerky. I've uploaded the last take which I think is less jerky; but unfortunately a bit blurry. I could upload the preceding take if you like or maybe you will want me to film another fresh video - hopefully this one is okay.