He also did one on the updated MPi81 version, they relocated the front sling swivel to the bbl nut and replaced the sling operated charging handle with a finger operated one. Other difference was the addition of a second short buffer spring at the rear, designed to up the rate of fire over the slower '69 version. The one in Ian's original video on top shows the lack of the spring on that one, but every '69 parts kit I have seen to date has had the second spring. They were also cut up new guns, so I suspect when Steyr upgraded the design they also added them to any of the older models they still had on the shelf.
Since they are not marked as to model, I also wondered if they didn't just convert existing guns to the new spec instead of making new ones. All they would of had to do was swap out 3 parts and add the spring. I can see them adding the spring first, making enough of the other (expensive) parts to convert a substantial number as a test, and when those didn't sell either just dropped the project and eventually sold them all off for pennies on the dollar.
I have always wanted one of these, the damn parts kits have skyrocketed in price. IIRC, they were initially offered for $99. I thought when they went up to $199 they were going to have them for a while. how wrong I was!