The connection is encrypted and I tried to change links in templates pointing to malwaretips.com so they use https. But some elements like embedded content from other sites, links in posts to images/pages stored on malwaretips.com without https, etc. will determine browsers to display that warning message. Once Chrome gets to a page on a site and displays that crossed padlock it will never change it even if you navigate to a page that should display a normal encrypted connection. Chrome is the only browser that does this. Some call it a bug, others call it a feature. Also mybb itself might cause that crossed-out padlock to appear on some pages, it could be more ssl friendly.
Since we do video reviews and we embed them in our forum, those pages will always determine Chrome to show the crossed-out padlock and as I explained above it will remain crossed due to how Chrome likes to handle things.
It is a shame since even a https with some unencrypted resources is more secure than a http connection. We might try forcing only the register and some login page to use https, but that would be less secure.