Restore Photos/Videos Back to iPhone Camera Roll
I finally resolved this by using iTunes Sync to add photos to an album in iPhone. It is only slightly different as my photos went back to a separate album, not Camera Roll but that’s okay. I noticed that the location name was restored and since it syncs Videos too, I’m sure slow-mo videos would work the way they should.

Also, latest Quicktime player on Mac plays slow-mo videos just like the iPhone.