The maximum file upload size is 10GB, but we suggest you don’t trouble yourself with uploading videos larger than 1080p as that’s the maximum size we render to for streaming at this time. We do not plan to expand to any higher quality in the future, so uploading at a higher quality is just time consuming for you & for our servers.
For those using a computer to edit content, a wonderful application for compressing videos is Handbrake. It is free. The fast 1080p mp4 preset is wonderful at creating a compressed file without losing much visual quality.