Hello, the media module only accepts direct links to the content, examples:
Image: example.com/image.jpg
Audio: example.com/audio.mp3 or audio.ogg
Video: example.com/video.mp4
Hi, if you use "Web Content" option (HTML) yo can insert images using the Data URI scheme (https://en.wikipedia.org/wiki/Data_URI_scheme#Examples).
Google for "image to base64", there are several online tools.