There's a reason websites put share buttons in prominent places. You need to capture that interest in the moment; forcing users to scroll around to find the button, as trivial as it may seem, reduces engagement.

If you're using your profile URL to link to YouTube, you're hiding the share buttons and leaving subscribers on the table. Whether it's a political ad or a web series, you want as many eyes on it as you can get, especially in the first 24 hours. Subscribers are opting-in to get notifications of your new videos; you should want to make that process as easy as possible.

If someone is clicking through to YouTube from your website, they're already interested. Capture that interest using YouTube's subscription center URL.

http://www.youtube.com/subscription_center?add_user=[YOUR_USER_NAME]

When someone who isn't yet subscribed to your channel clicks this link, your profile will be faded into the background, and they'll be presented with a box asking them to confirm their subscription. Subscribers are taken directly to your profile, so you don't have to worry about annoying loyal visitors.

Make sure to replace [YOUR_USER_NAME] with your actual YouTube user name. For example, my YouTube URL is

http://www.youtube.com/soderstrom OR http://www.youtube.com/user/soderstrom

So my subscription center URL is:

http://www.youtube.com/subscription_center?add_user=soderstrom

Click here to see the Subscription URL in action.