We recommend the following:

1) A bit-rate of 1000 Kbps

2) Video width of 640 pixels, and height corresponding to the aspect ratio. For a 16:9 video, the ideal dimensions would be 640 x 360, and for a 4:3 video, the ideal dimensions would be 640 x 480.
Note: the width and height of your source video must always be divisible by 2.

3) Format: while we support most major formats, in order to achieve optimal output quality, we recommend uploading videos that have been encoded using the H.264 codec, into MOV, or MP4. That being said, high quality AVI, WMV, and MPEG files work just fine too.