I didn't watch the second video, because I got far enough through the first video to see that the guy is giving terrible advice.
1. That's not the proper way to tie to a cleat.
1a. His method (putting in half-hitches) will weaken the line by focusing pressure on smaller sections of the line. The proper way to tie to a cleat will distribute the pressure across more of the line, while also increasing the areas of friction between sections of the line and the surfaces of the cleat, reducing any chances of slippage.
1b. Never ever wrap a line around your hand or fingers. You risk losing your fingers if anything moves the boat (wind, wake, current).
1c. The proper method requires only one hand to get to the point where the line is not going to slip and you have control of the boat. His method requires two. When there's any movement of the boat, you want one of your hands available to hold the boat with the line (but again, not with the line wrapped around your hand).
1d. You should go around both ends of the cleat before making the first diagonal crossover. Doing so will prevent line slippage, and this allows you to hold the boat in place if there's any water movement or wind, before you start your crossovers.
1e. Can I re-emphasize that you should NEVER WRAP A DOCKLINE AROUND YOUR HAND — especially if that line is only half-assed around a solid object like a cleat!!!!
2. The bow and stern lines should never be tight, unless you're using a line snubber. The spring lines — and you should always use two if you're going to use any — can be tight, but the primary lines should have slack. Why? Even if you're at a floating dock that moves with the tide, a rogue wave can still lift/drop your boat relative to the dock, and a short, tight line to the bow or stern could fail itself, pull the cleat off your boat, or pull the cleat off your dock.
If you look through the comments on the YouTube page for this video, you can see there are many people calling him out for his bad advice.