I was looking forward to this DLC, but with that caveat you are playing the console version so I have a few comments. Dragon riding is the worst kept secret for Skyrim DLC, not only because the original Skyrim teaser hinted at being able to do it, but also because a team of modders pulled it off months ago even if it was slightly hacked together, and made using some gravity based coding to pull it off.
In Bethesda's official version it seems like you still can't use spells or powers when mounted except the dragon's own breath weapon. In your video it seems like the player is more or less a pilot in a flight simulator call out ground targets. I hope to be proved wrong that there might be some air mounted combat though.
Ash Spawn? Looks very similar to a certain Monster mods already available on Nexus and Steam Workshop.
Bonemold armour? Yes it's made from troll bones because that was one of the toughest armours in the original version of Morrowind. Made trivial if you already have a high level Dragonborn in Skyrim. I think If you're reviewing DLC based on the original Morrowind you should have checked that out beforehand. Frankly for PC players this is nothing new - it already exists as a Morrowind armour mod pack on the Nexus.
Riekling spears? Novelty, misleading items that the PC mod community will most certainly patch to read properly as arrows. I've seen spear mods but they usually mimic two handed weapons replacing it with a custom odel and animation.