That's probably the post by @JamesLiu.
That one is also surface mounted. He purchased the flush mount as he wanted the wood grain faceplate and that option was only available with the flush mount (in-wall). Since he already had a power box and stuff in place, he built a small wood frame and attached the flush mount to that - effectively making it an 'on-wall' mount.
Makes by Mike is one of the only companies I know that has a flush mount available for retail. SmartHomeMount.com is also popular with the SharpTools community, but I think all of their stuff is 'on wall' mounts -- you could reach out to them and see if they offer a flush mount through their custom program.
When we were at CEDIA, there was a company called Wall Smart demoing some of their mud-in flush mounts. I think you have to go through a dealer though.
