You can organise a combined photo and video contest, at least partially. Participants can submit photos and videos in the same contest. But in the contest gallery, you won’t be able to see both photos and videos.
In the event that you would combine photo and video formats in your upload campaign, you will see this warning:
We thus recommend combining content types if your goal is only to collect user-generated content (UGC) and not to display it in a gallery afterwards. Otherwise, you will have to create separate galleries for photo and video submissions.