The Facebook Ads connector returns video_id but no playable video URL. Today the only MP4 is effective_instagram_media__media_url, so Facebook-only video ads have no playable video.
Please add a field with the Graph API source for the creative’s video, including asset_feed_spec videos. Meta returns it from GET /{video_id}?fields=source called with the owning Page’s access token. You already request pages_show_list and pages_read_engagement, which this needs.
For us, 4–30% of video ads per account have no Instagram video, so they show only a thumbnail.