Johann Maree, presently you can upload video in several ways.
- using "Add new" button on the Video page and embed existing videos from video sharing sites.
- Add video link to Newsfeed and the system will grab and show the video preview. But unfortunately not all video sharing sites allow to parse video to get the thumbnail. Presently this valid for the youtube and vimeo videos.
If you would like to suggest a kind of new feature for video plugin, feel free to submit your improvement at Oxwall uservoice:
http://oxwall.uservoice.com/forums/13756-ideas-for-oxwall . We use the uservoice platform with its voting system for proposed features, which lets us set priorities in the dev plan if the demand really exists - the bigger the score, the higher the priority. The eventual decision will be made based on the number of votes a suggestion received, while other ideas are skipped for the time being, generating more traction with the community.