Are you trying to recover or fix a from a camera or a backup database? AVI files: Explained | Opening and Using AVI files - Adobe

This likely refers to a specific clip numbered 15 in a batch, formatted in the Audio Video Interleave (AVI) wrapper.

When a file requires being "fixed," it typically suffers from one of three common architectural failures: 1. Broken or Missing Index

If the internal data is healthy but the container is damaged beyond a quick index repair, "remuxing" is the answer. Using tools like FFmpeg, you can extract the raw video and audio tracks out of the broken AVI wrapper and place them into a brand-new, modern container like an MP4 or MKV without losing a single pixel of quality.