: You can use the 9zip app mentioned in your query, or standard alternatives like 7-Zip or WinZip .
If you have a file or a set of files with these labels, they are likely parts of a larger video file that was "split" to meet upload size limits. To open them: VID1-9zip
: This often appears as a naming convention for the first video in a series or as part of a file fragment (e.g., .z01 or .001 ). : You can use the 9zip app mentioned