You're using a relatively ancient camcorder format on a very old version of the program -- but on a 64-bit Windows 10 machine.
That may or may not be why it's not working, but these are definitely contributing factors. Which I'm sure you've figured, since the program used to work on your older computer. Among the other contributing factors is the fact that older versions of the program activated certain components the first time you used them -- and, since most of the web systems that activated these old components have long been taken down, it's possible that there are vital components in your old program that simply won't fully deploy.
But that said, have you got Quicktime 7 installed, per the program's system requirements?
Version 9 requires you to manually set up your project when you first start a project. When you did that, which project settings did you select? If you don't remember, go to the Edit menu and check under Project Settings.
If we can determine that you've got everything in place and properly set up, one simple workaround may be to change your video files' suffixes from .mod to .mpg. MOD files are essentially MPEG files, so this may trick the program into recognizing the video.
Yeah, I've been afraid that the older program and video format might actually be the source of my troubles. I have tried the "change the file extension" trick to no avail. I get the exact same message when it's listed as a mpeg file as a mod file, oddly enough. I do have Quicktime 7 installed. And here's a screenshot of my settings.
Well, your project settings aren't even remotely close -- which may or may not be contributing to your problem also.
Start a new project and select for your project settings Hard Disk Camcorder/Standard 48khz -- since your video is just 720x480 MPEG/MOD.
That may not fix your issues, but at least that part of the workflow will be right.
Any interest at all in dropping $150 on a used/refurb AVCHD camcorder and $50-$100 on a post-version 11 version of Premiere Elements? I think you'll find it will make your video editing life about 1000% much easier.
Damn, that didn't work, either. I may in fact have to get a newer camcorder. And potentially a newer version of Premiere. Oy.