This plugin is designed to access a youtube feed and display it in a WordPress Widget.
Look for "Youtube" under Appearance -> Widgets. Drag it into a sidebar, type your Youtube name ex:EsotechInc into Youtube "Account or ID", select User or Playlist, then choose the number of videos you wan't to display. Click Save.
Caching keeps a local copy of your videos at the interval specified so you don't have to constantly contact Youtube. This saves on site load speed because you don't have to make an external connection.
Try disabling the cache, saving, refreshing the page where you widget displays, then turning cache back on. Cache saves data into wordpress, so updating settings won't reflect until the next cache update.