Unable to copy Pics from Windows PC to iPhone using iTunes.

I'm a new iPhone user so wanted to transfer my old phone pictures and videos that I copied to my windows PC to iPhone. I followed the guides on internet and yet when I use the Add file or Add Folder option, it reads up the files that are there but does not show up any files for transferring to iPhone.

Morever, it is showing these videos under the movies section which appear only when iPhone is connected so I am assuming these files are on iPhone but not on my PC. I do not know how these got transferred but they dont show up in iphone, they show up on itunes when phone is connected to windows pc. I tried changing the path of photos to sync but these videos stay there constantly. I've tried the photos app and TV app on phone but these videos do not show up there.

So please help me delete these videos if they are on phone but not visible since they are eating up a lot of space for nothing and also help me to transfer my photos from windows pc to iphone.