What’s in a molecule? – the science of macaroni salad from TED-Ed (3m 15s).
Some information on solids, liquids and gases (including a decent animation) can be found here. And this is a video on States of Matter from The Virtual School:
Science Bank 4 (Motion of Particles): Part 1 – Brownian motion (to 4m 45s); Part 2 – diffusion (to 9m 45s); Part 3 – changes of state (to 14m 15s):
IGCSE Chemistry: Topic 1 part 1 Particulate Nature of Matter (6m 30s) & part 2 Diffusion (5m 35s), lessons by Sal Sciab.
Not on the syllabus, but interesting: the invisible motion of still objects: