Uses for an iPhone 2G that can't connect/sync to iTunes, but charges & works just fine
If it's jailbroken, and you are looking to get movies and music to it, then can you scp them onto the device? 

So first I would check I could ssh onto the device when it was on the same wireless network as my laptop.  Then (assuming scp works anywhere that ssh does, not sure there) I'd scp files I wanted to watch over (possibly converting them with Handbrake first) and then use iFile (from cydia) to navigate to the file and watch.  

If iFile is not available because of the operating system, you might have to work a little harder to put the files into the correct place for the iphone native apps to find them.