Some YouTube videos are configured by the YouTube channel owners to automatically receive completed subtitles from Amara. (Please note that by default subtitles are NOT synced from Amara to YouTube - to make this happen, the channel that hosts the video must be linked to Amara as described here)
If a video should send completed subtitles to Amara, you will see "Synced" tag opposite the video's URL on YouTube on URLs tab:
Warning: subtitles should be synced to YouTube after the subtitles have been finished and marked as complete. However, this may happen with a delay - if YouTube server gets too busy and would not accept the subtitles, Amara will automatically keep retrying every few minutes until the subtitles get synced.
If you see that the video is tagged as Synced, but none of its subtitles gets pushed to YouTube, please notify Amara stuff at firstname.lastname@example.org.