If you're in certain countries (like the US), you might have been shown a new video ad for My Little Pony: Tell Your Tale on YouTube today.
The video itself was uploaded unlisted to Hasbro's YouTube channel several months ago, but the ad campaign seems to have started today to coincide with the release of today's new episode.
The video URL of a YouTube ad can be obtained using the "Copy debug info" / "Stats for nerds" options of the video player's right-click menu, so that's what I did. You can watch the advertisement below.