The videos are all hosted on vimeo.com and have the same settings. They are embedded in the website and should be equally viewable if you have access to the page. I chose Vimeo as there should be less problems. At the moment about 2% of my customers have reported problems. Still is a bummer if you are one of them.
Different browsers and settings for those can cause problems, as well as wifi connections, the browser's cache, and other things.
Your download speed from your internet service provider is very important when watching my HD videos. If the video is not loading properly you can turn off HD by clicking on HD at the bottom of the videos. be surprised to learn that they're only getting a fraction of their service's advertised maximum speeds. For example, your Internet service provider (ISP) might have you on a plan that says "up to 30 Mbps down" while you're really only getting download speeds of around 19 Mbps.
Web sites like www.speedtest.net offer free tests for both the upload and download speeds of your Internet connection, but be cautious of some of the tempting "start" buttons in ads on the sites -- many are actually well-designed ads that look like they're part of the site's test mechanisms. You want to click only on "BEGIN TEST". Before you call your ISP about any discrepancies, remember that the plan you're on is based on a maximum value. Your actual results are affected by factors like your ISP's peak Web use times, the number of people sharing your line and your distance from the ISP's fiber pipeline.
If you have taken the test at speedtest.net linked above you see a number like 15.25 Mbps, more or less. Less than that and you could run into problems playing back HD videos. Even with 6 Mbps you could still play back my videos, but it could be choppy as your speeds vary depending on the time of day and traffic. If you experience problem you can always pause the video and wait a few minutes, or turn off HD by clicking on HD at the bottom of the videos.
From time to time there are customers with problems viewing videos, but generally they solve the problem following the advice from Vimeo at https://vimeo.com/help/faq/watching-videos/playback-issues