Youtube
Video ID
[0-9A-Za-z_-]{10}[048AEIMQUYcgkosw]
- int64 - 编码后 11 位
- ChannelID
[0-9A-Za-z_-]{21}[AQgw]
- URL Safe Base64 - https://webapps.stackexchange.com/a/101153/74685
- 判断是否有效
http://gdata.youtube.com/feeds/api/videos/VIDEO_ID
[0-9A-Za-z_-]{10}[048AEIMQUYcgkosw]
[0-9A-Za-z_-]{21}[AQgw]
http://gdata.youtube.com/feeds/api/videos/VIDEO_ID