The URL http://www.bilibili.tv/video/av636603/index_2.html does not work yet.
It turns out that the function did not work for outputs longer than 1024 UCS-2 tokens. Write non-BMP characters one by one to ensure that we count correctly.
It uses the same system as discovery.com
It doesn't use rtmpdump now.
The ID now starts with PL, so we don't need to output that twice.
It allows to download some videos that failed.