Your subject line says "Mov files" (which are video files), but your message talks about scanning old photos. I'll address the old photos issue.
Because there are so many dates/times associated with photos, and because every program feels free to use its own names, it's critical to be pedantically precise about terminology. The date/time a photo was originally taken (when the shutter was pressed) is called Date/Time Original or Capture Date. The date/time a photo was transferred to digital media is called Date/Time Digitized (when the analog file was scanned or when the digital-camera shutter was pressed).
A good rule of hygiene is to ensure every photo has a Date/Time Original (capture date). Typically only digital archivists care about maintaining Date/Time Digitized. If you ensure that every photo has a Date/Time Original, then pretty much any modern app and Web site will order your photos correctly.
In LR, you set Date/Time Original using the Metadata > Edit Capture Time command. By default, LR won't write the capture time back to the file's metadata, so depending on how you are transferring photos to other programs, the capture time won't necessarily get transferred. So you either need to do Metadata > Save Metadata To File, or better, set the option Catalog Settings > Metadata > Automatically Write Changes Into XMP.
Unfortunately, LR's Edit Capture Time isn't very flexible with dealing with scanned photos in which the precise date/time is not known. So some people like to set an entire batch to, say, 1963/10/01 00:00:00, while others like to have each photo set in increasing increments of 1 second, so that programs will at least maintain the known relative ordering (which comes from the film or slide ordering). To do that, you'll need a third-party plugin, e.g. ExifMeta or CaptureTime To EXIF.
Sorry John a very "Senior Moment" from me. I got muddled between two issues I have.
You answered the scan problem very well thank you.
However I have the same issue with some "Mov" files in the wrong date order and would love an answer to that on if possible.
LR's support for video metadata is very weak. It can read some of it but it will never write changes back to the video file. So you can use Metadata > Edit Capture Time to change LR's internal notion of capture date, but no other programs will see that changed date. You could use the Exifmeta or Capturetime to EXIF plugins to set the capture time in the video file's metadata, which will allow other programs to see the updated times.
Also, you could add your vote and opinion to this thread about video metadata support in the official Adobe feedback forum: Lightroom: Metadata applied to videos in Lightroom isn't available in other applications