How to add youtube comments with link

Hi BHW members, sorry for my bad english but I'm sixteen year old guy from Poland and I'm some kind of noob in Internet Marketing and Earning at all.
I have seen a lot of journeys in BHW where people added comments in YouTube to gain some extra traffic. I would like to do this too, I bought some YT account but I can't add comments with link. Why some people can do that and I cannot.
There are plenty of comments with links, so why I can't do the same?
Thank you for all help and I hope you understood me.

You cant add links to youtube comments.

just shrink the link with bit.ly. Make sure that you post it in bit.ly\xyz format not bit.ly/xyz.

Site (dot) com can work too on yt.

You can use Unicode to change a part of the link. YouTube does not recognize Unicode and does not flag it as link.
In example you can make google.com to google．com and YouTube will allow you to post it. It doesn't look exactly right, but all browsers recognize it as normal link so "right-click, go to" works with Unicode.
Here is a generator were you can enter any letters you want and convert it to Unicode: http://www.linkstrasse.de/en/%EF%BD%86%EF%BD%95%EF%BD%8C%EF%BD%8C%EF%BD%97%EF%BD%89%EF%BD%84%EF%BD%94%EF%BD%88%EF%BC%8D%EF%BD%83%EF%BD%8F%EF%BD%8E%EF%BD%96%EF%BD%85%EF%BD%92%EF%BD%94%EF%BD%85%EF%BD%92