How does the Roozz browser plugin achieve it's cross platform capability

Question

I came across the browser plugin from roozz.com and I tried it out with LinqPad, try it here. They say there is a conversion process that takes basically any exe and converts it to their platform which can then be run on windows, mac, linux through all major browsers.

When I dug into what was going on, at least for LinqPad on Windows 7, all it did was download the linqpad exe to my user AppData/Local folder and host it inside of chrome. Interestingly I could just launch the exe outside of the browser and run it normally. I was even able to uninstall Roozz plugin and keep launching the app like normal.

The main questions I have.

1. Is this really cross platform, can I run a .NET 4.0 WPF app on windows, mac, and linux, or are you only able to run windows apps on windows and mac apps on mac?
2. In general, what is this plugin doing and what are the limitations?

EDIT: Just to clear up, this isn't as much about how browser plugins generally work, but rather how this one can run apps exclusively written for one platform and run on an incompatible one.

Further testing revealed that there is some BS around their claims, or at least some confusing "hype" because LinqPad does in fact not work on MacOSx. When trying to run the app you get,

"Your operating system is not supported by the Roozz platform yet. But we are working on it."

Answer 1

Let me clarify a little in 7 short points:

1. Roozz is a platform for distributing software on the web. Software which your users would normally have to download and install on their system and keep updated etc. It just makes life a little easier for your end users.
2. The smart thing about Roozz is that you don't have to rebuild or reprogram your apps to run on this platform. Roozz can convert most apps, target for the desktop to run from a webpage. FireBreath is an a framework that help you build your own plugin - (FireBreath is a framework for the "I do everything myself guy")
3. Next month Roozz will also have a build in Rental system, such that you can rent the application running on the Roozz Platform per hour or per day. Again these apps can use this payment system without having to integrate with SDKs and APIs. (no need to rebuild) In this case apps will not be stored in AppData/Local folder
4. Roozz can run applications written for Mono and .NET on multiple platform (Win, Mac and Linux). But only if they were build to run on Mono already. LinqPad uses some features that are not in Mono, thus it does not work cross platform yet... (in this case Roozz will make sure that the right version of .NET or Mono is available on the end users system)
5. If application have been build and released both for Win and Mac platform, then the Roozz Plugin will fetch the right version from the server and then you will be able to run the application both on Windows and Mac in the same webpage/URL (note that it is actually not the same binary, that run on Mac and Windows in this case)
6. The Roozz Plugin for Mac is still not released in public (only in private beta). The reason being. Developer requests have not been very strong as Win and Linux versions cover more than 90% all desktop Internet users today. OS Statistics
7. Roozz is not trying to do what nobody has done before => Turn native windows apps into Mac and Linux apps without recompiling at all. Roozz is merely trying to propose a easier way to handling distribution of software both for end users and developers.