When you arrive at the second tab screen in the video wizard, the screen will look like the image below:
On this second screen there are three settings we need to review:
Height - This is the overall height, in pixels, of your video, as it will appear on the published Web page. Increase/decrease this value using the up/down arrows appropriately, or simply over-type the value in this text box with the exact height you wish to use.
Width - This is the overall width, in pixels, of your video. Increase/decrease this value using the up/down arrows appropriately, or simply over-type the value in this text box with the exact width you wish to use.
Keep Aspect Ratio Option - If checked, this checkbox will ensure that whatever changes you make to one of the options above, the other option (width or height) will automatically update as well in order to maintain the 'aspect' of the video.
What this means, in other words, is that the 'proportions' of the video will remain intact so long as this checkbox remains checked.
If you uncheck this checkbox, you will be able to make changes to either the height or width of the video independently of one another, and your output video may end up being stretched and/or distorted.
Once you have set the values above, click the 'Next' button at the bottom of the window to proceed to the next step in the video insertion process.