Originally posted on YouTube in 2013, this is essentially still the method I use today. These days, Debian includes an official Firefox and Thunderbird package (rather than Icedove and Iceweasel), but they are not up-to-date with the latest Mozilla releases. This instructional video accompanied my blog post:
https://linuxtechhowto.blogspot.com/2013/07/installing-official-mozilla-builds-of.html
