Microsoft AVI and ASF
AVI (Audio Video Interleave) and ASF (Advanced Streaming Format) are Microsoft video container formats from the 1990s. They have largely been replaced by MP4 and MKV. Use VLC Media Player to play these files on macOS.
What File Juicer does with AVI and ASF files
File Juicer recognises AVI and ASF files by their file header when the extension is missing. This is useful for files recovered from browser caches or other sources where files are stored without their original extensions.
For more about WMV-encoded video in these containers, see the WMV page.