Okay, Christopher, I know what the problem is with this. It's the merging of Google+ with Youtube last year. Accounts made after that don't have a /user/... so the forum plugin doesn't recognise the channel name.
There is a fix for it. You have to follow the steps below:
1. When you're logged in to Youtube, click your little icon in the upper right (next to the bell), and then click on the little gear symbol next to the "Creator Studio" box. This will take you to your Youtube account settings.
2. Below your name, with your email and your avatar, you'll see an "Advanced" link. Click on it. This will take you to your Youtube User ID, and your Channel ID. Both are long strings of text and numbers. And neither will work with this forum plugin.
3. Click on the "Create Custom URL" link and a box will pop up giving you a blank field to insert text and numbers of your choosing. This will change the URL of your channel to one with "/user/" in it, which this forum plugin WILL recognise.
4. Put the text you entered in the custom URL field (make sure you confirm the creation) into the Youtube field in your profile here. Not the full link, just the text you entered.
For example, if you entered something like "transitioningchris" into the Create Custom URL field on Youtube, then it would give you a link of https://www.youtube.com/user/transitioningchris. You only need to enter the text after the last / into the field here and it should link to your Youtube channel.
