This guy is right on! You should learn new skills that are critical to your success instead of focusing on your business. Just making a website is easy, making one that is easy for your users to navigate, captures your users' interactions, feed that back to a CRM so you can act on it and setting up automation to handle each one properly so you don't lose the customer is not. (And do not forget, the design of your site is critical to the effectiveness of Google and Microsoft Ads. Without them, no one will ever see your new, beautiful site.)
ADA website compliance is about making sure that everyone has equal access to all the elements on your website and apps. That may mean you need to provide alternatives for some of the functions and content on your site in order to meet ADA website compliance standards. Here’s a quick rundown of some of the accommodations that need to be incorporated into your website to meet the ADA guidelines:

In an August 2016 case involving the University of California Berkeley, the DOJ ruled that the public university was in violation of ADA Title II (similar to Title III but it instead applies to government organizations) because their YouTube channel’s videos didn’t include captions for hearing impaired visitors. The DOJ found this to violate the ADA as deaf users did not have equal access to the online content.

ADA disabilities include both mental and physical medical conditions. A condition does not need to be severe or permanent to be a disability.[6] Equal Employment Opportunity Commission regulations provide a list of conditions that should easily be concluded to be disabilities: deafness, blindness, an intellectual disability (formerly termed mental retardation), partially or completely missing limbs or mobility impairments requiring the use of a wheelchair, autism, cancer, cerebral palsy, diabetes, epilepsy, Human Immunodeficiency Virus (HIV) infection, multiple sclerosis, muscular dystrophy, major depressive disorder, bipolar disorder, post-traumatic stress disorder, obsessive compulsive disorder, and schizophrenia.[7] Other mental or physical health conditions also may be disabilities, depending on what the individual's symptoms would be in the absence of "mitigating measures" (medication, therapy, assistive devices, or other means of restoring function), during an "active episode" of the condition (if the condition is episodic).[7]

Web developers need to keep this in mind when creating websites. The best screen readers use naturalized voices and alter tone and inflection based on HTML tags, so choose layout elements carefully. It is also important to keep in mind that navigation is significantly slower when using a screen reader than it is for sighted people. Sighted people don't have to wait for the reader to get to the link we want- we spot links quickly and are able to navigate to our sought items, often without having to do any reading at all. Minimizing graphics also helps shorten reading times and speed navigation for disabled users.
Web designers often design in such a way that does not allow the user to adjust font size or color. While they may be protecting their brand, they are also inhibiting some users. Many visually impaired need to use high contrast color settings or very large fonts to read a website. Don't design your website in a way that makes it impossible for them to do this. 
UPDATE: Since writing this post in August 2017, several important changes have taken place in the laws regarding ADA compliance for websites. On December 26, 2017, the Department of Justice announced that they have withdrawn the Obama-era Advance Notice of Proposed Rulemaking mentioned in this article which intended to require ADA website compliance. The DOJ’s withdrawal announcement stated, “The Department will continue to assess whether specific technical standards are necessary and appropriate to assist covered entities with complying with the ADA.”
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.
So, what do I mean by that? That sounds weird. So, when I say designer, I mean someone who's strictly an artist, and there's a lot of those out there. A lot of 'designers' are only concerned about the aesthetics of the site. What it looks like, or if its unique, or if it follows the latest website design trends. But at the end of the day they don't really 'get it' when it comes to what the primary purpose of a website is.