How to add a background behind a video? how can you add a background image with a video in Blender?
 I would like to use a video from the screen of my phone (the size is in "portrait" mode), and add a background to fill the rest of the screen, so that it can fit the size in youtube.
Thanks

Edit: here is a good video that explains how to proceed (videos 11 and 12) : https://www.youtube.com/watch?v=x_dy4yMSJSw&amp;list=PLjyuVPBuorqIhlqZtoIvnAVQ3x18sNev4&amp;index=12
All you need is to add some strip at the bottom of the sequencer.

To add a solid color add a Effect Strip->Color and place it under your video strip.