install the drive on a pc as a second drive and copy all the files to a folder on your pc. open the video0 file and select all, then delete.
shut down and and install the new larger drive into the pc.
reformat the new drive to fat32 then copy all the files from pc to the new drive.
now shut down pc, remove drive, and install into the dm and restart.
ive done this to several dm ds2 machines and it works fine.
ive noticed it depends on machine as too how large you can go . in your case i think id just replace the small drive instead of adding a larger second drive.