Ditching your Windows or learning Ruby and/or Python shouldn't give your career a boost in the long run, unless you're developing for iOS/OSX/Linux or in Ruby and/or Python.
If a company is going to not continue with an interview because you use Windows, they might not be a company you want to work with (if you really like Windows, which I do). I'm actually quite surprised to see somebody who is so bold as to say a Windows user is a non-starter. I think this is very small minded, particularly as most end users are likely on a Windows PC, even if they have an iOS or Android mobile or tablet device. Developing for linux servers is a bit nicer on OSX, but if you're more comfortable on Windows, and can make it work for you, than that shouldn't be an issue.
As far as scripting languages go, I've got a bit of experience with Ruby and Python, as well as PHP, but I'd say my go to language of choice is Javascript. Java is still a hugely popular language, and there are so many others.
Basically, I think this presenter is trying to give 'start-up founders with little technical knowledge' the ability to screen technical people, but I think that is really difficult to do without knowing what type of technical position the person is hiring for. He also likely has some geographic bias. I live in Sydney Australia, where Rails devs seem quite rare, while Java and PHP still seem to be in vogue. When I was in North America, Ruby on Rails was the big thing.
I'd take a look at where you're at right now, what you want to be doing, and plan from there. I think you can mostly ignore this guy.