People can get access or modify your files.
edit
To process multiple input files simultaneously using ffmpeg, you can use the "concat" filter to combine the input files into a single stream. This allows you to apply various processing options to all the input files at once.
In general you do not. Nearly all executable files are coded in a computer programming language, and then compiled into executable files. So to modify an executable, you would need the source code for the program, you would modify the source code and then recompile into a NEW version of the executable. Linux does provide for an executable script file, but these are more scripts than executable files.
You can use ffmpeg to process all files in a folder simultaneously by using a command that specifies the input folder and the desired output settings for the files. This allows ffmpeg to batch process all the files in the folder at once, saving time and effort.
A batch converter is a tool that converts several files simultaneously to one format. These can be files or any data.
an area in Photoshop were all the image files appear simultaneously
Anything you want. It's similar to a CD-RW. You can fill it with files, modify the files, delete the files, put in more files, or erase the whole thing.
To make it harder to delete, modify or move them by mistake.
It means that the file is protected so that you can't modify it
If a user has write permissions then that user is able to Delete or Modify that file. In the case of directories it means that user can create, delete, modify files in that folder.
Computer server system