This article describes what video formats are supported by the Video Widget, and gives examples of how to convert to a supported format.
What is Supported?
The Video Widget is designed to work with .WEBM and .MP4 videos that are encoded with the H.264 codec. We recommend that if you want to show a video in your Presentation, you provide a video file in this format.
One thing to keep in mind for multiple monitor Presentations, is that MP4's have a resolution limit of 2048x2048 pixels. This means that is the largest resolution your video can be. WebM's do not suffer this limitation, and can show a video up to the resolution of 10000x10000 pixels.
How do I convert to .MP4 and encode in H.264?
Handbrake is free to use on Windows, Mac, and Linux.
How do I convert to .WEBM?
Adapter for Mac can convert to .WEBM and is free to use. There are also many web applications that can convert to .WEBM online, such as Zamzar.