We used to sell our courses on DVD in the old days, before the cloud came of age. We made the decision to move to online delivery (sometimes called cloud delivery) at the beginning of 2013.
Cloud delivery offers huge advantages. For example, it has enabled us to make our videos available in HD (with over 60 hours of tutorials this would need around 15 blu-ray disks), it has also enabled an interactive search facility, progress logging (so you can keep track of which lessons you have watched) via a powerful server-side database and many other features that would be impossible with a Blu-Ray or hard-drive installed application. And we have many other incredible new interactive features in development that will massively improve the learning experience.
The other problem with DVD (or Blu-ray) delivered courses is that they are always out of date. For example, Microsoft have made huge changes to OneDrive and the Excel web apps just in the last six months. We can update our courses instantly using online delivery.
The other huge advantage of cloud-based applications is that they can be used on any device (Apple Mac, Android, iPad, Windows PC etc). With an old-fashioned offline app you’d need a different app version for each device (and often for each operating system version for each device). Cloud also enables settings to follow you around. For example, if you watch a video on your iPad, when you return to the office you’ll see that same lesson logged as viewed on your work PC.
On my own mobile devices it has been a long time since I’ve been unable to connect to the Internet (either by using using mobile data or using free WiFi hotspots).
The only place I cannot access the Internet these days is (as you have pointed out) when travelling using an airline that has not yet implemented WiFi (40 of the world’s major airlines currently offer WiFi on their flights, many for free).
It is worth asking the airline you have chosen whether they have WiFi available on the flights you are taking. Failing this, our entire courses are also available from Amazon as low-cost paper printed books (click books on the top bar for direct links to Amazon pages). The books are #1 best-sellers and cover exactly the same lessons as the video courses.