Then if people clicked that, the video will received that like. If they are not loggedin, then they are going to be redirected to youtube login page and after they are logged in(kinda of authentication), they will redirected back to the video and have their like counted.
Thanks for your suggestion. We are going to look at the possibility of this and if so where it would be placed. Currently, users can like a video through other sites like Facebook and Google+ by clicking the REACT button of the player. Perhaps we could incorporate it with the other REACT options if it is possible.