Update: we fixed what's causing this, so any new video uploads won't experience the same frozen, out-of-sync audio issue. If you've been waiting to post–go for it! We're now in the process of fixing all impacted videos, which will take a bit more time. Appreciate your patience!https://twitter.com/TeamYouTube/status/969298199658733568 …
Have you tried these steps: https://goo.gl/bqA3k1 ? Also, let us know if disabling add-ons or using another browser fixes the issue.