Yeah, crap advice all around in that vid.
Honest tips should, in my humble opinion, go something like this:
1. companions should wait outside of whatever dungeon or area you're wanting to infiltrate. They're only useful if you've caught the attention of a few enemies and can reasonably expect them to give chase. The way the AI's made gives the impression that NPCs can't really leave their cell of origin, but I've seen plenty of well-armed bandits leave their fortress and spawn outside because I derped around too much. Stealth builds can be fairly glass cannon-y if you're not careful, so telling your follower to regroup as soon as possible, once you leave, is a good plan.
2. it's slow as shit and it sucks, but you should never, ever run in an enemy-infested area, and always sneak. You want to boost that Sneak skill as fast as you possibly can. The only spell you need is Muffle or one of its stronger variants. Bow sneak attacks are fairly easy to land, but don't invest in your One Handed skill immediately. You'll probably want to use daggers for close range, but daggers are fairly weak. Take your time and level One Handed up, even if you don't really invest in it (Sneak, Sneak, Sneak!). You need to do that if you want to be able to triple the damage output from dagger or sword sneak attacks.
All things considered, your main areas of expertise should be:
- Sneak
- Archery
- One Handed
In that order. Feel free to mix and match, but using heavy armor is counter-productive if you don't invest in it from the very beginning. You'll want to negate your defenses' produced noise as much as possible, and that's harder to do with everything from Iron to Dragonplate Armor. Considering this, Light Armor comes highly recommended.
3. stick to shadowy areas, and freeze in place if low-level enemies suspect something might be up. Even if you're in the dark, the AI can pick up your movement. Avoid notching arrows *while* an enemy's close by. Try and always notch your arrows pre-emtively. Watch your surroundings carefully, and avoid bumping into anything. Even disturbing a pickaxe on top of some measly crate from across the corridor could be picked up by the AI. For that very same reason, don't pick up anything or raid any corpses until you're reasonably sure you've cleaned out the area.
4. as an ancillary skill, both Alchemy and Enchantment are great picks. You'll obviously want to make poisons, and slapping on a strong, custom-made enchantment can be useful. Just be sure to carry a second primary weapon designed for soul-trapping if you do, and carry an ample supply of Soul Gems.
5. pray for Beth to add archery kill cams in a future update. That would be epic, and joining me in that vain hope makes a badass out of you. Because I said so. Yeah.
6. stop saying "Rouge". "Rouge" refers to either a Sonic the Hedgehog comic character or a synonym for lipstick. The word you're looking for is "Rogue", as in "Rogues gallery" or "My, this young lass is quite the handsome rogue!"