Discussion about Dungeon (Dark Elves).

Very easy. Just move the file to the folder My Documents\My Games\Heroes of Might and Magic V — Tribes of the East\Profiles\Your profile name\Replays. Then, launch the game and watch it as usual.
Regarding alt-grade units, I don't think Dungeon has any units that are completely unequal. I recently thought that the new lizards were complete garbage, but after using them, I realized that they look pretty good in the early stages of the game. You can simply run around the opponent and deal, say, a quarter of the damage, but without taking any damage in return. And then, use the bite ability and the already safe attacks of the Furies, and the classic Minotaur + Lizard combination can be easily applied. And when there is a chance of encountering an opponent, you should switch to the old cavalry units.