Thank you for your answers. I forgot that the computer I use for this purpose is Linux. I was worried with Windows, so use Linux on a spare laptop for this activity. Worry with metadata and those personal identifiers.

I use exiftool for images, but it does not work with MKV. I can try Ffmpeg to see if any metadata comes back. But I worry not just for metadata. But also same for any other parameter that is in the file itself. Metadata is outside, might be other identifiers encoded in the file. The two things are my big worries.

I try hex editor some other person posted, but don't know how to read it.

Thank you for your help.

Thanks. I am same.

I try a Hex viewer program on my Linux. Here is a snapshot with some parameters hidden with black. That is just the title of the file. Ex: "My Movie.mkv"

Most of this is encoded and I don't understand what I'm readingg. Is there a way to translate this?

It is very large hex file. But I scroll through it and I have not seen anything that identifies me. Things like computer name, OS, IP address, date and time. But I am not sure as it is large file.

Edit: Not sure what went error with my snapshot. It got cut off but you can still see parameters.

Sorry, I mean I am on Linux for this specific computer. I try on LInux because I'm worried with Windows, but don't know.