Your video is being transcoded.

Before a video is fully transcoded, creators got a sub-par streaming experience while doing a test-run of the customer experience.

A few people were unaware of this, so we added it to the streaming experience (for creators, pre-transcode only).

We had some fun with CSS to imply the sort of visual artifacts they may be seeing: http://codepen.io/anon/pen/Brhac