August 23, 2018
Note: This is a deprecation announcement for the showinfo parameter. In addition, the behavior for the rel parameter is changing. Titles, channel information, and related videos are an important part of YouTube's core user experience, and these changes help to make the YouTube viewing experience consistent across different platforms.
The behavior for the rel parameter is changing on or after September 25, 2018. The effect of the change is that you will not be able to disable related videos.
The showinfo parameter, which indicates whether the player should display information like the video title and uploader before the video starts playing, is also being deprecated. Following the change, the channel avatar and video title will always display before playback begins, when playback is paused, and when playback ends. The avatar being displayed is new behavior that will be consistent across all embedded players.
What all this really means is that the thumbnail image of your small embedded video will be completely obscured by 24-point type and happy user faces and links to other videos so that you can't actually see the thumbnail of this video. It's just fantastic.
Sure, it's a minor annoyance, but for fuck's sake, why would they do this? (That's a rhetorical question. We all know the answer is that some shitheel ran an A/B test and found that if you cover everything with links, some people are going to accidentally click them, and then you have more clicks and that's all we care about, right? Clicks clicks clicks clicks.)