I use MANY mods in my Skyrim game, but as Lakeview Manor is my primary player house, I have several for that area and for the manor itself. This is a quick playthrough to showcase the mods I use, which are listed below-
Lakeview Upgrades- http://www.nexusmods.com/skyrim/mods/36117
Creates purchasable walls, defenses, guards, and other accessories that are added to the steward's store list. VERY highly recommended, as it gives you what you need to keep your homestead safe without going overboard.
Lakeview With Main Hall Library- http://www.nexusmods.com/skyrim/mods/36191
Responsible for much of the interior you saw, including the upstairs library so that you do not need to sacrifice an entire wing of the house to such. Also highly recommended, and comes with an in-game diary you can write in using the Creation Kit.
Unofficial Hearthfire Patch- http://www.nexusmods.com/skyrim/mods/25127
While you don't see much of this in the video, I recommend it and all of the other Unofficial patch mods that are pertinent to your game. I resisted using them due to a kneejerk defiance to peer pressure, but when I finally added them in I had a LOT fewer issues with the game in general and Hearthfire especially. We all know Bethesda is sloppy about quality control, being more obsessed with meeting deadlines than producing bug-free games, so these are damn near mandatory for Skyrim players.
Lakeview Manor Road- http://www.nexusmods.com/skyrim/mods/27377/
Many mods incorporate this, but even by itself it is a handy addition to Lakeview manor.
Guards On Your Home- http://www.nexusmods.com/skyrim/mods/29467
I modified this significantly to change the guard outfits, but the gist of it is that it adds a few guards and tents for them to sleep in to each Hearthfire home. Bloody handy when your kids are out playing and a giant or bandits nip by for some mayhem.
Shezrie's Hearthfire Kitchens- http://steamcommunity.com/sharedfiles/filedetails/?id=185841041
A lamented loss from The Nexus, requiring people to use Steam Workshop (*shudders*) to acquire it, this converts that poorly-designed and pretty much useless room at the back of the main house into a useful, well-designed and awesome kitchen.
Lakeview Manor Basement Bedroom- http://www.nexusmods.com/skyrim/mods/41854
If you're like me and use multi-follower mods such as UFO, AFT, EFF or the like, then having this is a handy way of having crash space for your followers. In addition, if your character is a vampire, it adds a hidden vault for your coffin.
Spiffied Lakeview- Treasure Vault- http://www.nexusmods.com/skyrim/mods/46888/
My friend and fellow modder Spphy (I pronounce it "Spiffy" :-D ) put this together using AlCiao's vault resources, and I tried it out to be supportive. I actually really like it, and have kept it as an integral part of my Lakeview Manor mod profile. It adds a vault that displays piles of treasure directly proportional to the amount of gold you deposit into the vault.
Lakeview Manor Fish Hatchery- http://www.nexusmods.com/skyrim/mods/31549/
One of the things that annoyed the hell out of me is that Lakeview Manor is on a bloody giant lake full of fish, and only the ice-blasted wasteland Hearthfire home has a fish hatchery. This fixes that, and has an option for a mill as well (which I don't use as it conflicts with other stuff I added).
Convenient Horses- http://www.nexusmods.com/skyrim/mods/14950
Used for the dragon bone armour on my horse, but also a VERY useful mod for Skyrim players.
Pocket Empire Builder- http://www.nexusmods.com/skyrim/mods/30948
Oh, where to start... You can place a metric butt-tonne of things- buildings, walls, fortresses, people, guards, furniture, landscaping, etc.- while IN game instead of having to use the Creation Kit. Takes some skill to get placement right, but once you've gotten the hang of it this becomes an invaluable resource for those who want to change the world around them a bit.