You are trying to reinvent the wheel, gentlemen. Anything lower than 700MB will become unwatchable. 300MB difference. How much time you are going to save - not very much!
Your answer if FTP. There are plenty of open source free clients and servers on the internet. And since your son is running a server he might already have the server - you'll just need a client.
And of course, as mentioned above, sneakernet is always an options where distances allow
Edited to add: regarding compression, or rather archiving, since your goal is to reduce amount of data to be transmitted, I'd recommend WinRAR. Way better then any of the competitors. But then again, it costs money so maybe not worth getting your hands dirty.