Sphere Live is an audio video conferencing product built in Delphi Firemonkey by a team in Russia. There is an interview on a Russian blog with Alexey Glyzin (a developer from the team) and he outlines how and why they used Firemonkey to complete the project. The interview is in Russian (so use Google Translate on it) but it sounds like one reason they picked Delphi is because of the amount of different functionality that their application needed (200 modules). The interview states that Delphi is one of the languages which makes managing that amount of code easier. It mentions that they use the RealThinClient SDK components and that they have used Mitov VideoLab components in the project before as well. Most of the project is native Object Pascal with only a few libraries in C. It was important for them to have components that run on all platforms (Windows, OSX, Android, and IOS) and Delphi Firemonkey allowed them to do that. Lastly in the interview it is discussed what custom components they had to build (subclasses of TImage, TListBox, and TTreeView to name a few) and that the source for those may be released at some point.
Head over and read the full case study interview about building Sphere Live with Delphi Firemonkey.
Or check out the English translation of the blog post interview about Sphere Live in Delphi Firemonkey.