You can upload the following image formats (non-exhaustive list). Non-websafe image formats (other than JPEG, PNG, GIF, WEBP, SVG) are converted to PNG.
BMP, EPS, GIF, ICNS, ICO, IM, JPEG, JPEG 2000, MSP, PCX, PNG, PPM, SGI, SPIDER, TIFF, WebP, XBM
You can upload any video format but non-web format videos are transcoded to MP4. Library users can preview the following formatted videos only:
WEBM, MP4, OGG
For any other format HTML <video> supports, see Media type and format guide: image, audio, and video content.
Almost any file that is not virus-infected.