it makes perfect sense but it also makes sense, at least in my head, that since the whole drive was formatted for the Mac, that a PC computer would not be able to read the whole drive.
Now, I take it that the thumb stick has the capacity to hold the .mov file but because the restrictions of only allowing 4GBs you can't move it?
If so, have you tried splitting the file? HJSplit would help and then, after you have save that file you can connect the drive on the pc and format it again so it works for windows.
I am having similar problems with my 2TB goflex, my laptop just doesn't want to assign a letter to it but, I don't want to highjack your thread and I have already posted my problem on another thread.