iMessage synching in Yosemite 10.10.5 Is there a way to prevent iMessage from downloading all the messages and attachments to each of my Apple devices?  If I send a video from my iPhone, it goes to my laptop, my iPad, the iPad mini, my iMac and my tower.  I am on a Verizon hotspot so I pay exorbitant fees for bandwidth and it is useless for it appear everywhere and expensive.  Or, is there a way of just blocking incoming files?
As far as I know, your old data does not sync between devices, only new messages from the point which the device was setup. 

That being said, with each iOS device you have, you may have to just disable syncing or use different iMessage addresses. 

Do this from the iOS device:


Go to Settings
Select Messages
Select "Send and receive" 
Select which account you want to use on your device (whether its phone number, or email address). 


This would cause it to not sync across all other devices, but would also mean that you can't receive messages at all of your devices either.