First of all, I did never ask for any way to obtain illegal things; I only asked for ways to alter certain things that I had gotten through possible less-legal ways. I understand illegal software obtainment information is not allowed here and am in no way trying to encourage or ask for that either. (By the way, FYI, downloading movies is 100% legal in Holland )
Anyway, after a few days I’ve found a solution to my ISO problems.
To edit ISO’s, you need either IsoMaster (I think it is free) to open the ISO files, then to add the files you need, then to create a new ISO, or PowerIso (which isn’t free - but you can try to download it somehow, I won’t tell you how though). PowerIso is a really good one, because it can open, extract, mount, create and burn ISO’s.
To create one DVD from multiple ISO’s, I used PowerIso to extract the files from all the ISO’s to one folder per ISO. Then put those together into one file using IMGBurn Build mode. I ended up with 5 folders containing all the files from their respective ISO’s. When I mounted this with DaemonTools, the ISO was NOT bootable, but I could manually select all files, and so I could also run setup etc. so it did work, but the autorun option does not work.
For the movies, I still don’t know how to do it. I want to be able to create one DVD per season, with a menu, without having to convert all the .AVI files (or if I have to convert them, in such a way that they are not bigger than they are now).