为什么fastdfs开启防盗链，图片有效，视频不需要token仍然可以播放或下载？

Question

if use token to anti-steal

default value is false (0)

http.anti_steal.check_token=true

token TTL (time to live), seconds

default value is 600

http.anti_steal.token_ttl=900

secret key to generate anti-steal token

this parameter must be set when http.anti_steal.check_token set to true

the length of the secret key should not exceed 128 bytes

http.anti_steal.secret_key=FastDFS1234567890

return the content of the file when check token fail

default value is empty (no file sepecified)

http.anti_steal.token_check_fail=/home/yuqing/fastdfs/conf/anti-steal.jpg

另外Nginx安装了fastdfs模块用于下载，为什么图片和压缩包都可以被有效限制，我的mp4文件不需要token就能播放下载？