Or if your competitors are using the standard languages and tools, and you're using a language that provides significant abstractions on top of the standard languages and tools.
I was on board with your comments until I watched the video. Their language looks to be a jump on the order of assembly to C.
Why so negative?
Perhaps there is some room for radically new implementations; something along the lines of Erlang, which makes it possible to do what is quite difficult with other languages.
I think there is more room in frameworks for existing languages, but still, an order of magnitude seems quite dubious to me.
I'm actually not at all negative about new languages (I hack on a simple one myself), startups just don't strike me as the place for them. What they're doing does look cool, but what happens when you need to process an image, or send email, or talk to a different database, or deal with any of the other various things that are often covered by language extensions? Maybe this would have been better as a hack/framework on top of Javascript.
Did you see the bit where they can drop into raw Javascript at will?
I guess without actually seeing the code behind it, it's difficult to really say with certainty.
Yes, but the difference is not one order of magnitude. Not if there is some level of sanity in the language (e.g., I am not talking about brainfk). For example, even though one can program faster in Python, it is not 10 times faster than in C, especially for large-scale software.
I will however finish with, there's a reason C applications don't have features or agile development cycles, and it's not because the coders are absurdly productive. Also, please don't ever try to be a manager.
The only way you are going to get 10x, with roughly equivalent people is if someone is using a wholly inappropriate language (Ruby vs Forth for web apps, say), or if you can avoid writing libraries because someone has already written them.
This is one of the positive network externalities involved in programming language economics: the more people involved, the more likely it is someone has already written the code you need. Of course, these effects are not so strong that everyone gravitates to only a few languages, but they are certainly a consideration.
By writing your own language, unless it makes it very easy to take advantage of some other language (the JVM languages are a good example), you are pretty much guaranteeing that you will have to do this work yourself.