Scientific Eye – Rocks – a 19m 8s video:
Want2TlkScience? – a 10m 29s video on Rocks:
Also Science in Action – Rocks (18m 46s); Scientific Eye – River of Rock (20m) & KS3 Bitesize – Changing Materials – a video covering differences between Physical & Chemical Changes, Dissolving, Expansion & Contraction & the Rock Cycle.
Here is a spectacular Volcano vid from National Geographic.