diff --git a/doc/README.xsendfile b/doc/README.xsendfile
index 96ec5653b..bdf40aef6 100644
--- a/doc/README.xsendfile
+++ b/doc/README.xsendfile
@@ -24,3 +24,13 @@ XSendFilePath /var/www/seeddms51x/data/
 If the XSendFilePath is not set propperly, you will notice an error message
 in your apache log file, probably telling you that the download file could not
 be found.
+
+A positive side effect of xsendfile is support for content ranges which are
+currently *not* supported by seeddms' Download and ViewOnline scripts. This is
+especially usefull when previewing videos. Without content ranges it is not
+possible to jump to certain time in the video.
+
+In order to check if the xsendfile module is loaded, php uses apache_get_modules()
+which is only available if php is loaded as an apache module. Running php in fpm
+mode will prevent php from checking for xsendfile and consequently xsendfile support
+will not be available.