How to convert huge size to DVD9?

Hello.

I have an iso file which is highly compressed to 7 GB and also includes .md5, .dvd, .dvdid (I guess those are for recreating the original files from the iso).

I want to burn that iso file to a DVD9 (8.5 GB) and I have already tried but failed many times and kept wondering why.

I recently discovered what's wrong when I manually extracted the contents from the iso file...they have the insane size of 75.5 GB.

Is there a way to compress or something that huge size to fit it to a DVD9 without losing any content or quality?

I would prefer doing it from the iso file without the need of manually extracting it, because I have many iso files of the same kind.

I tried using dvd shrink but it can't even read the iso file or the extracted folders (it produces an error message).

The content is video with menus (audio_ts, jacket_p, video_ts) and the weird thing is that its source is from a DVD9 - I have no idea why it has that huge size, I am not the one who ripped it.

Thank you in advance.