I am attempting to use AVFoundation to record video on OS X but it waits till then end of the recording to save the file. I want to be able to have it save whatever it has captu
You can ask AVFoundation to vend the frames to you as it is recording, then just pass a set number of frames to the server. But what you are asking about is extremely complicated to get right, since bandwidth or temporary network blips can cause delays/skips, etc.
We had a discussion about doing this exact thing over here, by using AVCaptureSession with AVCaptureVideoDataOutput to vend the MPEG frames: Near Real Time Video Upload from iPhone
If you want the individual chunks to be playable, you'll have to wrap them in a MOV or MPEG container, but it doesn't sound like you need that in your scenario.