We are currently looking into this recent addition on eBay where you can add video much like adding an image to your listings. It is not yet available in Auctiva and we do not have a firm date for such being available at this time.
In the meantime, if you have video uploaded to YouTube, there is a tool to get eBay acceptable HTML which you can add to your description prior to posting. The tool is available here: https://www.isdntek.com/tagbot/YouTubeConverter.htm
You can then place that in your description where you want the video to show by clicking the Source button on the description editor and adding the video HTML where you want it to appear.
Should you have questions about this or encounter any difficulty, please feel free to file a support case so our agents can have a look at what you are working on and assist you.