Well, from my (limited) amount of research, metal skates weren't really in use until the middle ages.
But the SCA, that the person mentioned in the original post belongs to, IS concerned with the middle ages! Though admittedly, if the article you cite is correct, not until the late middle ages.
I wonder though if the archaeological evidence is complete. I suspect it, like most archaeology, is based on relative little evidence. E.g., is it possible that in the early middle ages, any iron - or other usable metals - were valuable enough that the used skates would not usually have been thrown away, but their metal would have been reused for other things? So we might just not have a sample. In fact, the early picture was drawn from an old map, not from an archaeological dig.
You don't really need sharp edges or metal to ski or skate (e.g., even now, many skis have no metal, and some speed skaters deburr the edges created by flattening the bottom). What you mostly need are smooth relatively flat surfaces. And that certainly could have been done using bone.
I'm rather bothered by the reconstructed skate that the article you site pictures. It has a ROUND bottom. One of the main things that makes skating (or skiing) efficient is to have an approximately FLAT bottom. But it is only a reconstruction.
Come to think of it, those early map-derived pictures show something that lies a bit like a snow board. (In fact, having just one ski or skate makes a pushing pole much more plausible. Is there any way to use a snow board efficiently when not moving downhill?)
Of course, when it comes right down to it, there isn't all that much difference between a ski and a skate.
Some early pictures and characterizations of "skis" make it clear that people were using two skis, sometimes without poles, long before the middle ages - e.g., see
http://r.search.yahoo.com/_ylt=AwrC1FPAF9JbO0cAkGBXNyoA;_ylu=X3oDMTByOHZyb21tBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNzcg--/RV=2/RE=1540524096/RO=10/RU=http%3a%2f%2fjournals.sfu.ca%2fnr%2findex.php%2fnr%2farticle%2fdownload%2f160%2f154/RK=2/RS=z2SRoaHS9qcUEOZOfKbaaKX5fH8-That article suggests they may have been using something vaguely akin to the "diagonal stride" technique - somewhat similar to modern skating technique - in Scandanavia - about 4000 to 4500 years ago, based on cave art, though I'm not sure that cave art is really clear enough to support that in a rigorous fashion. (And if they were going up hill, it is hard to believe they wouldn't have evolved something close to modern "herring-bone" technique, which is also somewhat similar to modern skating technique.) It is hard for me to believe they weren't also skating with them in a similar fashion on ice. If they did indeed go back to a mono-skate technique with a single between-the-legs pushing pole, that was backwards progress, in terms of efficiency.
But, since the picture of people skating that way was only from a drawing on an old map, perhaps the depiction of a single ski with a between-the-legs pushing pole was a non-eyewitness idea of how it worked, and maybe it was completely wrong, somewhat like the depictions of various imaginary creatures that appear on many old maps.
Obviously, neither of us are experts on the pre-history of skating. We can't really be sure of the early techniques and equipment, especially on areas where the experts disagree.
But I think we can both agree that the original poster's video doesn't look very efficient, and that few people would have used skates that way if it consumed so much energy. And I bet that if you wished to, you could the SCA skater a few lessons on skating technique, and maybe on shaping and/or sharpening the skate, that would make him much more efficient, and help him to have more fun with his home-made skates.