Device memory is device memory.
system memory is where apps etc are stored, which would be application memory.
I dont have smaple movies on my bold, and as far as i can remember never have, but I very much doubt they were 72MB.
72KB possibly, hence why the file free is the same.
"That's it then. Cancel the kitchen scraps for lepers and orphans, no more merciful beheadings... and call off Christmas."