Generally this can be done but there are some disadvantages:

• there's a filesize limit (4GB)


• you can't store any special file attributes like owner, permissions etc (this shouldn't be a problem for documents and videos though)


• some sync tools like rsync don't work well when they can't check or set some of the files' attributes


• old filesystems like FAT are more prone to fragmentation and file corruption

As an alternative you can install an ext3 driver on Mac/Windows or use NTFS (which doesn't suffer from problems number 1 and 4).