Watch: Why the Chinese model has caused shockwaves

Chinese AI bot DeepSeek has disrupted the stock market, with US President Donald Trump calling its rise "a wake-up call" for the US tech industry. DeepSeek - which claims its model was made at a fraction of the cost of its rivals - has become the most downloaded free app in the US just a week after it was launched. The BBC's AI correspondent, Marc Cieslak discusses why the large language model has caused shockwaves.