That really depends on what bitrate the media is being transcoded to. If you transcode to 4Mbps 720p, a 2 hour movie will take on average about 1.5GB of space based on the testing I’ve done. 8Mbps 1080p will be roughly double that, 3GB for a 2 hour movie In an ideal world most of your clients will be direct playing/direct streaming anyway, but if you have to transcode due to bandwidth limitations or shitty clients, you can use these numbers to gauge roughly how much space you might need.