In regular expressions, how to exclude a specific character? :     {"url": "http://res1.icourses.cn/share/process17//mp4/2017/3/17/6332c641-28b5-43a0-894c-972bd804f4e1_SD.mp4", "name": "1-课程导学"}, 
    {"url": "http://res2.icourses.cn/share/process17//mp4/2017/3/17/a21902b6-8680-4bdf-8f47-4f99d1354475_SD.mp4", "name": "2-计算机网络的定义与分类"}

I want to extract `6332c641-28b5-43a0-894c-972bd804f4e1_SD.mp4` and `a21902b6-8680-4bdf-8f47-4f99d1354475_SD.mp4`

How to write a regular expression to match the string at this location?