You can upload multiple images at once, but not video.
Please note that only one image per step is allowed in Teachme Biz.
Therefore, every image will be added as a separate step in the manual.
Please refer to the following manuals on how to create multiple steps with images at once:
▼Create multiple steps with images at once (Web Browser)
https://teachme.jp/8/manuals/4929561
▼Create multiple steps with images at once (iOS version)
https://teachme.jp/8/manuals/3204659
▼Create multiple steps with images at once (Android version)
https://teachme.jp/8/manuals/3204813
▼Create multiple steps with images at once (Windows Desktop App)
https://teachme.jp/8/manuals/3204998