He will give you all kinds of technical details on why you should do it this way and not that. You will see one, two or three different brands of oil that he "highly recommends" as being the best for your kind of riding. Then he will remind you to "like" this video and "subscribe" so you'll know when he produces new ones.
Let me just say this, if you ride your bike on a regular basis and occasionally get caught in the rain/snow you will need to both clean your chain and apply oil. The reason to clean it is to remove all the crap that splashed onto it from the road or trail. That crap will get inside the chain and through friction, wear it out. Then you will have to replace it. Chains are not
When you clean the chain, you will (should) need to clean everything that the chain interacts with. Mainly the gears on the wheel, the derailleurs and the front gears. What you use to do this cleaning is up to you. Personally, I use a can of Varsol and a scrub brush and rags. Then I will hang the chain to dry and blow out any stuck gunk with a compressor (while wearing safety goggles) Don't do this sort of maintenance indoors if you can avoid it.
Yes, this means that you need to remove the chain from the bike. That's what I do but you don't have to if you don't want to. Having said that, if the chain is extremely dirty, have the chain removed and cleaned by a mechanic. Doing so will result in a much more thorough job. In some cases, I will remove the chain and leave it submerged in Varsol while I work on the other parts of a repair/tuneup or even leave it submerged overnight.
Case in point, recently a client brought in a bike that he rides literally every single day. This resulted in a staggering amount of dirt and grime clinging to his entire drivetrain. With the understanding that I would have to charge for the time to clean it, I removed all the parts and thoroughly cleaned the drivetrain. The end result of all that dirt was that the pulleys on the derailleur where destroyed. The teeth of the pulleys were ground down to points because of the friction action. Since finding pulleys for this specific derailleur was not possible, it meant that the derailleur had to be replaced.
Keeping your drivetrain clean is important, as was shown in this extreme example.
Lubricating the drivetrain is a simple task of one or two drops on the inside of each chain pivot, and a drop on all the pivots of the derailleurs. Then, for good measure, I remove the housing from the cables (while still on the bike) and grease them. This assures no rust will develop and gives a smoother cable action. My clients appreciate it. What's important here is 1: keep the chain and everything it touches clean, 2: lubricate all pivot points with bicycle-specific lube. (no, WD40 or sewing machine oil is NOT the proper choice) When in doubt, consult a mechanic. Like me. Okay, go riding now. Spring has FINALLY arrived.