In order to make videos accessible across most devices, we can only accept a single type of video file: h.264 video with an AAC audio track, in an MP4 container.
The easiest tool to use to encode video in this fashion is Handbrake. It is available for Mac OS X, Windows, and Linux.
Videos are presented inline on CLN at 298x171 pixel dimensions, but you are welcome to provide a larger video for better viewing in full‐window or full‐screen. Please be conscious of the file’s final size and do not exceed 50 MB in size so other users can view the video without having to wait overly long for it to load.
Additionally, when you’re encoding the video, please make sure to check the “Web Optimized” checkbox. This will enable the video to begin playing before it finishes downloading.
For more information, please visit Video on the Web – Dive Into HTML5.