All the video editors use their own file format to store the video, effects, tracks and all the specific details each software needs to work. In order to upload it to Internet or use in a standard video player, you need to export the video to a standard format. This is called often as export or render.
There are lots of formats. The most important you need to know is that a video file is a container where place the video, audio, subtitles or other information. Each one of these parts is coded with a codec.
For compatibility, we recommend MP4. But for store it with free software and without problems with future players could be interesting to save also in Ogg. One of the things you have to choose is the aspect ratio of the video. Nowadays we have panoramic screens with formats like 16:9 or 16:10. If your recording has not the same aspect ratio, the video editor can deform the image or retail to fit it in the output aspect ratio. We recommend to record and export in 16:9, the recommended aspect ratio of Youtube and others.
Other choise is the resolution, for 16:9 we have many possible resolutions, but choosing a resolution bigger than the camera resolution doesn’t have sense. The minimum recommended is 1280x720 (720p).
We have to say that services like Youtube transform and enhance the video to their own prefered format. You have to upload it with the maximum quality your camera and video editor can record and you Internet connexion can afford in a reasonable time. You can maintain a bigger resolution increasing the compression, but the quality could be bad. We recommend trying to export parts of the project in many combinations of resolution - compression in order to find the best.