No, you cannot publish video directly to Spotify by uploading it to Fountain.
If you publish an episode through Fountain, the episode will be distributed as normal, but the video version will not automatically be uploaded to Spotify as a video episode.
If you want your episode to appear as video on Spotify, first publish the episode on Fountain, then log in to Spotify for Creators and upload the video version there.
Spotify explains that process in their guide for shows hosted on other platforms.
Publishing video episodes if you're not hosted with Spotify.