Level AA is a little more significant, and makes sites accessible to people with a wider range of disabilities, including the most common barriers to use. It won't impact the look and feel of the site as much as Level AAA compliance, though it does include guidance on color contrast and error identification. Most businesses should be aiming for Level AA conformity, and it appears to reflect the level of accessibility the DOJ expects. 

For discussion’s sake – while I don’t know the specific nature of your videos, my guess is that they might be demonstrating various techniques or other content in which simply hearing the audio of the video wouldn’t deliver the full context of the content. If making that content accessible is something you’d want to do, you’d likely want to start with a written description of what takes place in the video. Beyond that, high contrast vector images or diagrams showcasing specific parts of the technique would certainly help.
In recent cases, the U.S. Department of Justice has repeatedly sided with plaintiffs arguing that a private company’s website needs to be accessible, despite any other mitigating factors. One thing is for certain, however: The number of federal lawsuits alleging violations of the ADA is currently accelerating at a rapid pace. Between January and August 2017, there were 432 ADA lawsuits filed in federal court—more than the total number of ADA lawsuits in 2015 and 2016 combined.

Since March 15, 2012, ADA compliance with the 2010 Standards will be required for new construction and alterations. In the period between September 15, 2010 and March 15, 2012, covered entities may choose between the 1991 Standards ADA Compliance (without the elevator exemption for Title II facilities), the Uniform Federal Accessibility Standards (Title II facilities only), and the 2010 Standards ADA Compliance.
In court, Netflix tried to argue that websites should not be part of ADA compliance regulations, as there is no physical structure / location. They also argued that websites should not be in scope of ADA as there is no public component (the original ADA compliance law specifically called out that ADA rules apply primarily to services, locations, and products that are supposed to be open to the public).
Accessibility by UserWay UserWay creates a simpler and more accessible browsing experience for users with mobility issues. Millions of people cannot use a mouse or other pointing device and rely solely on their keyboard to navigate websites. Your site should be fully navigable using a keyboard’s tab key, arrow keys, the enter key and the space bar.

Regarding examples of accessible websites, I would suggest the Accessiweb gallery: http://www.accessiweb.org/index.php/galerie.html. Accessiweb is a reference list 100% based on WCAG2, and they deliver quality marks (the "Accessiweb label") upon website owners solicitation. The website undergoes a thorough manual review (on a carefully defined 10-page sample, more or less), and it gets the label only if it's flawless on every page. The level is reflective of the number of defects found and not corrected. Bronze is exactly equivalent to level A, Silver to AA, and Gold to AAA. So getting a Silver label means all A and AA tests were passed on all of the sample. Bronze, two stars: All A tests were passed, plus 50 to 75% AA tests. And so on.

Reha asked Vu if companies are obligated to comply? Vu said that unlike the physical access world, where any new building has to be compliant no matter what, there’s no such thing in the web world. The Justice Dept. hasn’t said that that’s the default, but they have said that the current regulatory regime requires it anyway. Equal access has been around since 1990.