Why can't I upload this large file to my assets or uploaded file section?
Assets and uploaded files have a 20mb file size limit. If you get an error when trying to upload a new file, check to make sure it falls within the 20mb file size limit.
Large files that have to do with content, such as .pdf and .docx files, images used for sliders and galleries, Flash files, XML files, video files, audio files, should all be uploaded to the Files page of your shop. Those files don't belong to your theme assets.