On Facebook the tags appear along with video description. The tags remain available after the streaming has finished.
On YouTube tags appear only when the video is live. To view the tags click the Live Stream tab in OneStream dashboard and click your live stream. It will take you straight to your live stream on YouTube. Click Edit Video under the video.
Here you can see the tags that are associated with your live video.
When you set tags and stream a video to Periscope, those tags appear alongside the video title in Periscope and in Twitter.
Tags do not work with YouTube Now and YouTube Existing Events