A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
In an earlier post or a link in an earlier post, there was information from YouTube, where they stated that they will serve ads to any videos linked to a third-party application. That pretty well puts the fickle finger of blame on them. Why the ads don't show up in other situations (Google slides, etc) is unclear; perhaps because they don't see other web apps as third party applications. Seems to fit that pattern, though.