There are definitely legitimate use cases for autoplaying media. Youtube would be annoying if you had to click play on every page. I think Facebook's implement

There are definitely legitimate use cases for autoplaying media. Youtube would be annoying if you had to click play on every page. I think Facebook's implementation strikes just the right balance. The video autoplays when it's in view, but without audio. If you want audio, you can click the play button to view it properly.