There is no way to copy photos in Lightroom. I think you want to Export the photos to that folder.
If the JPGs already exist just use your OS File Manager, Finder on Mac and Win/File Explorer on Windows, to Copy them to the specific folder you want/need them in for your video.
As long as you are Copying them LR won't be the wiser.
In LR you can Move them into that other folder "IF" that other folder is already listed, exists, in the LR Folders area in the Library module.
LR is not a File Manager or File Browser. Those type of tasks are best done in the OS's File Manager program.
There is a nice feature built into Lightroom for videographers. Lightroom works as well on video clips as it does on photos for importing, storing, previewing, tagging, etc. Once you've made a selection or collection of what you want, Export them. The key is using "Original" in the Video Format drop down. I put them in a project specific folder like "Vacation" and in a sub folder named Video Assets. If stills are involved, I do a second Export and put them in a sub folder named Photo Assets.
For video clips, the "Original" option makes exact copies of the original. If you really do make video edits in Lightroom you can export transcoded, reduced quality, clips.
When I open the new Project in Premier Elements, I make sure all the project files are kept in the same folder with the assets. It makes it easy to move or archive finished projects.