How to mount usb stick on HDMU image?

[morly]

you have to create a so-called "movie partition"
therefore you can either use the "Admin Tool" (see my signature) - then everything is done with a few mouse clicks,
or doing the following within telnet (usb stick connected to your box)

• format your stick with ext3 or ext4
• label your stick as "RECORD"
• on your created partition create a subfolder "movie"
• reboot your box with the flashpen still attached

Important: label- and foldername are case sensitive!