The text under the video provides a useful clue:
Find out more about volcanoes in Richard Hammond's Journey To... The Centre of the Planet on Tuesday 19 July, 2100 BST on BBC One.
Yepper, just call me Captain Oblivious. In my defense, I need the text size large so that bit was still below my view. Still it does show that I may need to reduce my Top Gear addiction for now.