A wolf can work if you back your character against a rock wall, because they will just attack without running around your character. This has worked with Skeevers, too.
Yay, I'm going to try this with Fast Healing! It seems like armor skills are the most infuriating, slowly-developing ones, at least in my playthroughs.
Unlike in Morrowind/Oblivion, Armor Skills/Block in Skyrim do not gain based on the sheer amount of
hits you take, but the amount of
damage that is absorbed by the armor/shield. Harder hitting opponents, like Mammoths and Giants, will level your Light Armor/Heavy Armor/Block
much faster than a weak foe will. But of course, there's also a risk of dying then too if the opponent is alot stronger than you.
In that video, it looks like he's on Novice setting, so the Mammoth is doing half damage (Which is why it's taking awhile to gain), and he probably has some +Health Regeneration equipment on.