I think we're confusing food grade cellophane wrap and freight/cargo wrap. That's what it looks like to me. Seems too big to be anything from the galley...
Did anyone stop to think perhaps the passports were collected by locals with no knowledge other than that some of the wreck was burning and they wanted to preserve them for the authorities to help with confirming identities?
Not everything must have an evil motive, it could be plain ignorance of crime scene protocol. As mentioned, many of the volunteers were miners and farmers from local towns.
As for tampering with the recorders- there is a photo of a guy carrying it. You really think they're going to try do something to them with the media knowing, recording and having them down as the first people to touch it?