Old Plugins – deletion

As plugins and WP versions improve the ability that used to be handled by older versions, or less effective plugins, some plugins could be redundantq12q2` – how can you find out which pages or posts are using which plugins?

Removing one layer of 3rd party should seem advisable. There are many media shortcodes for video. Most are not needed now with 3.6. How could I tell where all the old shortcodes are located.