I emailed the chap who runs the site and got a reply! He said he simply hasn't updated the site for a while because he's been busy doing other things. Great to know he's still keeping busy : )

The videos are even more impressive. For reasons known only to Google, 'rail bike' videos swarmed my YouTube feed a few years back. There are some stunning shots of going over trestles — GoPro held at arms length over the edge.