Unfortunately, the Showcase system won't allow uploads of files larger than 500MB. While this is the technical limit, it's worth aiming for smaller files if possible; the larger the files, the longer it will take users to download their showcases, and the more room it will take up on their devices - not ideal!
Large video files can usually be downsampled significantly without any perceptible loss in quality for a tablet screen. Check out how to compress videos here.
keywords: big filesize maximum