On FAT16 I think the limit is 2Gig.
On FAT32 it is 4Gig, (note that you can create files larger than 4G during a capture, but you might have problems
trying to read the data back from a FAT32 partition.
NTFS can create files as large as the available partition space allows.
Note also, that generally AVI captures are limited to 2Gig (according to the old spec), OpenDML AVIs can be larger,
but are still limited to 4Gig on FAT32 partitions.
I've started playing around with captures on XP using VirtualDub. And if I had thought it thru beforehand, would
have set up a large empty NTFS partition as the primary capture space.