Remember to FORMAT THE EXTERNAL/NEW Hard Disk as:
Mac OS Extended (mine are journaled)
as UNIX / DOS / FAT32 / Mac OS Exchange - works for most things BUT NOT FOR VIDEO - files will break up and to me impossibly to heal/mend.
I also prefer FireWire (or Thunderbolt) as USB/USB2 performs badly to me especially when filling up and even more so when HD-material is used !
Yours Bengt W
If you have problems in transferring the files to an external disk: first make some free space on your HD, then try again:
if Whatsize gives you the files form large to small, choose the largest in the list that you can be without: write down the exact name including the extension.
Close Whatsize, and all other unused apps, empty Trash.
Then start Terminal and copy/paste the following command in the Terminal:
rm /yourdisk/yourname/..full path../filename.
filename being the filename including the extension you wrote down, yourdisk being the name of your harddisk, yourname being your homefolder, full path the full path to the file.
Try again after this to move (CMD-Drag) files to the external disk. If not enough space do the above again.