You won't be able to put it back together on your external, though. Sure, you can use 7zip to split it into 3 smaller parts that will each fit on your external drive, but then you're stuck with three compressed archives which you can't play back unless you extract them to another drive which allows for larger files. Reformatting your external as NTFS would allow for filesizes up to 16TB, if you go for ext3 or ext4 (if your OS allows) the maximum allowed size for a file can go way beyond that.