Outputting with 50 frames per second of video is going to double the file size of a standard 25 FPS output for a start. You will be able to halve the size of the video straight away by reducing the frame rate to 25. As a Pro subscriber, you also have the option to render your scribes via our remote video rendering and hosting service sho.co. You can download your scribe video from sho.co in MP4 format at 1080 with 25fps and this will give you the smallest file size possible out of all of the rendering options.
For instructions on how to render via sho.co see Render and share scribes.