Hey @fnkngrv. How much knowledge do you have of any kind of basic coding, like HTML, CSS or MXL? If you know HTML it makes things easier for me to explain because you'll be more likely to know what some words mean when I say them. If it sounds like I'm being condescending, I'm sorry. I don't mean to be, but without knowing your level of coding knowledge, I'll have to dumb things down a bit just in case you don't know anything about it.
Lines 84-107 in the basvid.xml file are "commented out". That means that the system doesn't read them, and the don't interfere with anything else.
<!-- comments go in here -->
These are used for lots of things, like making notes about a section of code, or for keeping a copy of working code while testing new code.
The Carousel Mod lets you have a Horizontal carousel so you cycle the logos left and right (like the default carousel), or you can have a Vertical carousel that lets you cycle the logos up and down.
The BaseVid theme has code for both of these carousels, but you can't have them both active at once because they will conflict with each other and can break your theme, so the Vertical carousel is commented out. To view the Vertical carousel you need to comment out the Horizontal carousel code by putting
<!-- before the code and
--> after the code. You then need to remove those comments from around the Vertical carousel code.
In regards to the Views, EmulationStation uses different Views to display different data. The first View you see when you start ES is the System View. This is the one with the carousel of system. Then you have the Basic View which displays a list of games that don't have any metadata. There is also the Detailed View that displays the list of games that do have metadata (images, descriptions, genre, etc). Last is Video View which is virtually identical to Detailed View, except it can display videos. You can disregard Grid View for now, as I haven't heard anything about it's development for a while.
Line 16 of basevid.xml has
<view name="system, basic, detailed, grid, video">, which means that any code within this
<view> will effect all of the Views mentioned.
I can't remember if I already told you this, but all this information is in the Creating your own theme tutorial in the RetroPie Docs.