The charts are truly embedded (not linked) objects, so there's no question of missing external resources. But it appears that the charts are from Open Office or similar program, so unless you have the source program installed, you won't be able to edit them.
In case anyone's curious about how I arrived at the Open Office guess, I saved the original PPT as a PPTX, tacked a ZIP extension onto the file's name and opened it as a ZIP file. Within the zip, there's an Embeddings folder containing any OLE embedded objects. I dragged one of these out to the desktop and opened in an editor and found text referring to Open Office Chart.
And as @music2myear's mentioned: "Get 7zip and save yourself a step though. You can right-click on any file and extract it using 7zip without having to rename it to a compressible format."
Totally agree. It's free. As long as you're on Windows, not Mac, it's definitely the way to go. It natively understands Office 2007 and onward format files.