This was added to reward the helpful members who post great content that we can use such as GFX packs/templates/freebies, so if you use any of the content posted by our members, we ask that you hit the subscribe button and sub to them
But this button is also useful for people who post in the video promotion section, so that if someone likes your video, they can sub to you
Most users already have this feature enabled but in-case you don't here is how to enable it:
Step 1: Go to profile in the menu at the top of the page
Step 2: Scroll down until you find "youtube channel" which is highlighted green
Step 3: Enter the link to your channel there and click save
Thats it!, Now every time you post you will display a subscribe button which leads to your channel!