You can hyperlink on your Reddit posts or comments by using the icon that looks like a chain, which is available on both desktop and mobile devices.

But why can't any real-world object -- with or without a code -- be enriched by virtual information, accessible through a cell phone screen, a visor, or, looking even further into the future, ...

You can add a video to Google Slides from YouTube, or by uploading from Google Drive. Here's how to do it.