video "media created" time incorrect when files copied from Iphone to Windows Explorer

Image dates are local time but QuickTime based movie (.mp4, .m4v, .mov) dates should be UTC and the applications should convert them to the computer's local time. Time zones are the flies in the ointment.

Windows might report dates and metadata to its own liking.

https://exiftool.org/forum/index.php?topic=6591.msg32875#msg32875

If you install exiftool to your PC, the best way to check the datetimes is to use command:

exiftool -a -G1 -s -api QuickTimeUTC=1 -FileCreateDate -Time:All movie.mov

Video metadata is not particularly standardized, and so weird stuff shows up. This is some Exif metadata for a video I made on my Nikon a couple of months ago:

The movie was made on June 27 at 9:28 in the morning. Texas is 5 hours ahead of Universal Time.

Later in the Exif file it shows this:

There's no Time Zone here. So that might be it--since your movies are all off by the same amount, something in the process isn't dealing with the Exif data correctly.

It may be that you will need to find an Exif edit tool that works on Windows. On my Mac I have apps that allow me to batch change metadata, but you may have to hunt around. This is such a common thing, that Exif edit tools are pretty easy to find and fairly cheap.