I have a $300 13" Chromebook with a 1080p IPS display and I spot check some of my videos on it. I'm able to read the text outside. Although I try to position myself to not directly have the sun glaring on the screen. That would be an issue to read anything, video or not.
I'm always for improving accessibility. If it's not too much trouble would you mind skimming one of my videos to see what it's like on your main device? Here's a video on creating a GPG key pair: https://www.youtube.com/watch?v=1vVIpIvboSg
Your video appears to be all in the terminal, and most text is white on dark background. Plus the font is bigger.
Contrast this (pun not intended) with an example of a colorful code video (not an ide, but representative of what you see in a lot coding videos https://youtu.be/zC7TcrRi46Q (not to pick on the producer of this video... just grabbed an example). This example is unreadable in bright ambient light, and there are many videos with about the same colors and fonts. These are the ones I'm talking about.
In the video you linked I see what you mean. I haven't tested it outside but just eyeballing some of the screenshots in the presentation the blue function names are likely impossible to read, the dark orange / red module names could be borderline too since it's kind of dark text on a dark background, and even the green atoms are a bit similar to the background in terms of darkness. I'm not sure what color theme that is but personally I wouldn't use it.
I try to stick with One and Gruvbox. Both have pretty decent contrast ratios for both light and dark variants. I have 1920x1080 screenshot side by side comparisons of both with dark vs light in my dotfiles at https://github.com/nickjj/dotfiles.
I know this because I have tried, with three different modern laptops (two MBPs and an XPS) which have the best brightness available for laptops. If I hit dark mode content, it just has to wait until I'm indoors. But usually I'm looking for something because I need it at that moment. If I can't view on potential illustrated video, I will try the next one I can view.
People taking the time to produce content often do care about attracting and keeping viewers/subscribers, and this is a case where an accessibility issue will reduce the number of viewers.
I highly appreciate the effort people put into sharing their knowledge, but I find it really disappointing when I can tell that their effort is wasted on some potential viewers. I may be weird (no, I am, but that's not necessarily a negative), but I know I'm not the only person with this opinion.