As a Finn, I always find it amusing, that the first comments when this video resurfaces, are in the vein of "I'd like to see him cut..." and mention whatever wood they find to be hard to chop. I'm not sure I'm willing to defend an axe I've never seen in person, especially since I don't know most of the woods you mentioned, except in furniture stores. Finns are pretty set in their opinion that most hardwood trees are too valuable for firewood, and should be prioritized for carpentry and carving.
Most of the firewood for heating in Finland is birch as it burns hot and clean in the ever so prolific masonry heater (much more efficient use of firewood, as you don't need to maintain a fire 24/7 to stay warm), so is it a surprise that that's the wood the guy Mr. Kärnä uses in his demonstration? Finnish forests are pretty much spruce, birch, or pine, and most other trees are too uncommon to just burn away.
If I were to get a wood splitting tool, that isn't a Fiskars axe or maul (Fiskars is another Finnish company, named after the Fiskars steel mill in the town of, you guessed it, Fiskars), I might lean towards a Finnish "kiilakirves", which doesn't look anything like a maul. My Finnish grandpa has limited mobility by now (he relies on a walker or crutches for now, but a wheelchair seems inevitable), and he has had one of these for years. He is able to use this contraption sitting down, without risk of losing his balance, which to someone as reliant of self-sufficiency as him, is a big deal. Even a lightweight like me can make decent progress with such a tool.
http://www.oivakaihdin.com/kirves.html