Your video may not meet the listed requirements for the upload tool. Mediathread supports video files that end in .mov, .mp4, or .avi. Any other video should be converted to a Quicktime-compatible format before uploading. Submitted files must be less than 2GB.
You may try converting and compressing your video for web content or you can contact the Mediathread team to arrange to drop off your video: firstname.lastname@example.org
Tips for Converting
If you are looking for a free simple compression and conversion tool, download Handbreak.