首先，取得 json 網址，例如：
https://aaaaaa.akamaized.net/exp=xxxxxxxxxxxec38d/master.json?base64_init=1
改為
https://aaaaaa-adaptive.akamaized.net/exp=xxxxxxxxxxxec38d/master.mpd
#2
./youtube-dl -o abc.mp4 https://aaaaaa.akamaized.net/exp=xxxxxxxxxxxec38d/master.mpd
youtube-dl 官網：
https://youtube-dl.org/
youtube-dl github：
https://github.com/ytdl-org/youtube-dl/
參考用法：
https://github.com/ytdl-org/youtube-dl/blob/master/README.md#readme
https://www.cnblogs.com/faunjoe88/p/7810427.html
