Recently, the C920 has now been superceeded by the C922x Pro Stream model. In the revised C922, Logitech improved the circuitry to deliver higher frame rates. However, with a now lower street price, the C920 is still an excellent choice for Apple computer users wanting 720p or 1080p HD streaming and capture on MacOS.
As webcam resolutions increase - the demand on computer bandwidth becomes staggering, especially as we move from 720p to 1080p high-definition modes. It's just a TON of data to deal with. To keep data streams manageable - and to save significant disk space when capturing video to your hard drive, H.264 is a huge advance in reducing data size dramatically while preserving a very, very high quality image. It's so efficient and so good that it's been adopted widely across the computing universe, most notably and recently in the Blu-Ray DVD standard to deliver stunning images and still fit a feature film on disc. It's also one of the many CODEC's bundled into Apple's QuickTime software.
As it applies to Logitech's C920 web camera, Mac OSX users are getting the benefit of H.264 compression built into the webcam's hardware. That means a better experience streaming live video. And video capture will use less space on your hard disk or SSD, and make file uploads to sites like YouTube faster.