What a difference! And you don't even notice a quality change when playing the video. At least I don't. For anyone with a slow computer and a fast connection, there's really no reason to compress video files yourself. Just upload the files and let YT handle it.
The source videos here are not entirely RAW though, they just use very basic compression codecs. RAW files for decent resolutions take at least a few GB per minute, so unless you have very high bandwidth and storage space you'd better settle for a basic compression first, one with a resulting file size that suits your bandwidth, and let YT do the heavy lifting after that.