I'll copy my reply that went to another topic, but I think it suits here also:
It made me wonder on why did China change their stance when they were pro-bitcoin at November?
In my theory, the Chinese govt. thought at first that BTC could be a threat to dollar as an global currency. They thought that BTC could actually be a monetary system what is free from leeches of the western financial world. So, they thought that promoting BTC is actually good for China and therefor the piece covering/promoting bitcoin was shown on an chinese national news program that is known for government propaganda. And remember that the news piece was the actual start of this new rise that started in October.
Now, why did they suddenly change their stance at the start of December? I think that the reason was that they gave further studies into the nature of bitcoin and it's market system. They probably discovered the "public secret" that most of the BTC are actually owned by the same people who profit most on the success of the dollar. They discovered that most of the bitcoin is owned and the market system is run by groups from wall street. Then they saw that with promoting BTC in China, they are actually helping wall street players to rake up money from the Chinese people.
I think that they are now investing into building a new crypto that could actually fulfill the goals that they thought possible at first.
Looking at all the events in hindsight I think something different happened:
1) Yes, initially there was a lot of Pro-Bitcoin CCTV coverage, but I think that the government had no clue what Bitcoin was or they simply didn't care. Some journalists at CCTV were simply interpreting Bitcoin is something cool and it does not have a political agenda (at least it was interpreted in that way), so as long some air time is filled with something it is ok.
2) Suddenly, people got interested in Bitcoin because of these CCTV coverages and started buying a _lot_. Companies were also interpreting the CCTV news as government approval so they started promoting Bitcoin as well. The Chinese central bank (PBoC) has been quite angry that the dollar is regarded as world reserve currency (just look at how they promote IMF Special Drawing Rights, but without luck) so in some sense the positive Bitcoin coverage on CCTV could be interpreted that it had government approval.
3) However, it turns out that PBoC and Gov had no clue what Bitcoin was, but when they found out they were scared to death, because it enables Chinese people to circumvent the harsh capital controls. Hence, their stance on Bitcoin. To cool things down they didn't outlaw Bitcoin directly, but wanted to have things under control by restricting banks and financial institutions dealing with Bitcoin.
In hindsight this makes sense. Although, I think that Bitcoin is far superior than IMF Special Drawing Rights, but I think the Chinese gov would actually prefer IMF SDRs. The reason is that IMF SDRs are only used by governments and never by the people themselves. Therefore, it makes it much easier to impose capital control and Chinese gov loves control.
So to conclude: Chinese gov is probably aware that Bitcoin could be used to overthrow USD as world reserve currency, but it would also lose its own ability on capital control over its own currency (RMB). Currently, that is viewed as a bigger threat. However, if Chinese gov thinks that easing on capital control won't harm the power of the Chinese government, then I expect that they'll fully support Bitcoin and it would quite quickly declare it as world reserve currency. Whether that will happen or not is still an open question.