They probably cut out and pasted in the relevant parts.
However, it concerns me—and is illegal—to be able to bring up a classified document electronically and use that same PC to have unclassified, outside the organization connectivity, let alone a public email system connection.
So, they may have used a unclassified PC—that is, not cleared to allow classified data access—to bring up the classified data on that PC to transfer it, or allowed an illegal connection to the outside word on a PC on a classified network, that would have been approved to be on a classified network ONLY.
All of this should have been disallowed by policy and technological means.
Someone with administrator access may have allowed some illegal things to occur.
Now, I say may have, because it is still possible for the Secretary herself to transfer the data to a thumb drive and take it home, or let someone on her staff do so, BUT—since using writable thumb drives is illegal on classified systems, some administrator would have had to remove that policy on the Secretary’s or close underling’s computer.
See my post 64. I’m thinking along similar lines as you.
I think the tampering happened at the .gov level, not by personal staffers.
Abedin did have clearance:
http://www.politico.com/story/2015/08/hillary-clinton-email-probe-turns-to-huma-121314.html