properties> date created... I thought this meant the date the video was created, but finally realized that date changes every time I move, reorganize, even open a file. o
The existence of that piece of metadata is entirely dependent on the application that wrote the file. It's very common to load up JPG files with metadata (EXIF tags) about the file, such as a timestamp or camera information or geolocation. ID3 tags in MP3 files are also very common. But it's a lot less common to see this kind of metadata in video files.
If you just need a tool to read this data from files manually, GSpot might do the trick: http://www.videohelp.com/tools/Gspot
If you want to read this in code then I imagine each container format is going to have its own standards and each one will take a bit of research and implementation to support.
I used the following online tool: https://www.get-metadata.com It allows to upload a file and analyze it and then shows all its metadata.