If you have Images mode enabled:
- links ending in .mp4 and .gifv are now recognized and will autoplay, looping and muted
- links to youtube are now recognized and show with a youtube player. They do not autoplay, won't loop and will play with audio.
- any image or video that is expanded will revert back to an unexpanded link when it scrolls out of view.
(Note: linking to a specific time in a youtube video does not work at present, it will start from the beginning)
It goes without saying, but this feature is entirely optional, just set the webclient to No Images mode and they'll stay as regular links. And this does not give anyone permission to use such things ICly.