You're confused here. The entire blade is not made from a single piece of metal. Paramount blades are made from an aluminum-alloy chassis and a steel runner (two pieces total). The chassis is fabricated from a single piece of aluminum alloy: not a separate heel plate, a separate sole plate, and a separate body all attached together (that's a key point of the video). The runner is fabricated from a single piece of steel (Paramount uses 1085 plain-carbon steel, 420HC stainless steel, and 440C stainless steel). As I wrote before, the Paramount website does not specify how the runner is attached to the chassis; but, I read their patent, and it specifies an adhesive.
You are right. They clearly show the entire blade chassis, in early stage, with blade-holder, plates, , and say it was made from a single extrusion. I was fooled, because it looks in the final shot of that like the lower part of the holder is thinner - but, in retrospect, that haven't added the runners yet.
I think they are oversimpify the modern Jackson Matrix fabrication technique. In particular, I am pretty sure the new Jackson Matrix blades also use adhesive. Certainly in the screw threads, possibly also to hold the holder and runner together.
I am rather puzzled that the British government let MK and Wilson merge under the HD Sports label. They were at the time the main competitors in the high end figure skating blade market. Doesn't the UK have antitrust laws? They act as though there are now no major competitors - they keep raising the prices, big time, on their most expensive blades.
I really wish someone would give them more competition. For a while, it seemed like Jackson would, when they produced the Jackson Matrix 1 blades, with interchangeable runners. The runners "only" cost $130/pair (still pretty expensive), if I remember right. And they worked pretty well, even though you had to be very careful not to strip the (probably) aluminum bolt heads and threads.
But then Jackson Matrix went to non-interchangeable runners, and stopped making runners for Matrix I holders, and upped their prices to be in the same ballpark as MK and Wilson. Leaving those of us who had purchased the Matrix I blades stuck.
(I had planned to explore many types of blade styles at that somewhat reduced cost. But immediately after I bought one pair of blades, they stopped making them, so I quickly, and without a lot of thought, fearing they would run out, bought out Rainbo Sport's supply of Dance runners in my size - though it turned out that Matrix Dance were quite a lot different than the MK Dance I was used to - and also bought one pair each of Synchro and Supremes. The Supremes turned out to be beyond my skill to use - toe picks too aggressive.)
(I did try to modify a pair of Matrix Dance runners to match the MK Dance rocker profile - but I wasn't happy with the result. MK Dance also had thinline ground edge widths, and imitating that would have been my minimal shop skills.)
I wish another company would make interchangeable runner figure skates, at a reasonable price, and offer more-or-less clones of the rocker profiles and edge widths of the most popular styles from other companies - so we could all inexpensively experiment to find the best style for each of us. I think they should also have separate interchangeable toe picks, that could be added and played with. Even if that company couldn't do the highest quality metallurgy, it would have helped each of us find what we best liked.
I notice Cricut makes sewing cutters that guide where the cut occurs - basically low end CNC. If there were a home-sharpening machine that would do the same thing - have a grindwheel that was guided by a computer to cut a user-specified rocker profile and toe pick shape - at a few hundred dollars (it needn't be as fast and powerful as commercial sharpening machines), and someone sold blanks, we could experiment that way.
(There are European cross-cut skate blade sharpening machines that are computer guided somewhat like that as far as the profile is concerned. But I think they are designed for the heavy duty fast pro shop market, and they are quite expensive.
Oh well.
I assume, as far as the high end blades are concerned, HD Sports must know a lot about metallurgy, and that no new cheap blade company could match them. In part, because when people make their own high quality steel knives, they often start with discarded used MK Sports skate blades.