An hour of my FRAPSed video takes up about 120GB. Of course, I'm recording at 1920x1080 at 60fps. After a video is cut up and been through post, I can compress them down to about 500mb for 15minutes, or roughly 1GB for 30minutes. That is with 1080p quality, though. It would be significantly less if I only worked in 720p. My uncompressed video folder has over 400 GB of video in it right now; I'm hoarding some old clips until I finish making some new videos out of it. xSplit also compresses while it records, since it is primarily made for live streaming. However, the drawback to compressing in real-time is it takes a lot more CPU power than recording uncompressed. And even recording uncompressed is going to drop your in-game frame rates by a bunch.