1. This depends on your OS system and browser.
2. Currently, Amazon S3 is not yet available.
3. Following MIME types are supported: JPG, JPEG, PNG, BMP, GI, MP4, MPEG, MPG, OGG, WEBM.
4. The media library should go. When you transfer the video from Youtube, we can not do anything, the video must be loaded, please contact your provider and Youtube support.