When you try to move a video file in the Files tab to the Camera Roll of Photos app, it fails to move it with PHPhotosErrorDomain Error-1 message. The reasons for the failure are:
1. An audio codec not supported by iOS
If the video file has a file format or an audio codec not supported by iOS, it cannot be saved in the Camera Roll of Photos app.
For example, an MP4 video file is supported by iOS but contains a specific audio codec that is not supported by iOS.
2. Insufficient device capacity
While storing the file in the File tab of Send menu within Send Anywhere app, the file is copied and saved to the Camera Roll of Photos app and then deleted stored in the File tab. So in the process of copying to Camera Roll, you have to use capacity temporarily as much as the file size you want to move to Camera Roll.
For example, if the video file size is 10GB, you will need 10GB stored in the File tab of Send menu within Send Anywhere app, 10GB to store in the Camera Roll of Photos app, and a total of 20GB. After copying and saving the file to the Camera Roll of Photos app, it is deleted from the File tab of Send menu within Send Anywhere app, resulting in only using 10GB.