New Youtube hashtag feature

Hashtags have a strong effect in social media and youtube, but they acquired more power now in YouTube for its effect on promoting youtube channels and videos.

• Where can I write Hashtags in my video ?
  Hashtags can be written in the description box of a video, they appear above your title when someone click on your video, which will make your channel ranked up in search engines.

You may see this video for more info:

and this video for more details about : How hashtags work on your channel.

All the best.