The 2.x branch of Media: Wistia has been completely rewritten to use oEmbed instead of the Wistia Data API. Your API key is therefore no longer necessary and will be removed from the variables table when you upgrade. The module now supports both public and private videos, playlists, and Embed Builder customized players. It also validates URLs and embed code to see if the video or playlist they refer to actually exist on Wistia, and it caches video data to speed page loads.