Filter Forge 13 now supports loading video files right in the main window — the same way as you load a single image. To apply a filter to a video file or an image sequence, load it via the Source menu:
After you load a video and select a filter, you'll be able to see each frame preview on the Timeline:
Note: you can't change the video duration and frame rate – to do that, load the video as an Artboard background.
To apply the filter and render the resulting video, select File > Render Animation: the filter will be sequentially applied to all frames, and the rendered result will be saved as a new video file of the selected format.
The Render Animation command is only available in the Studio Edition: the junior editions can still save each frame one by one via the Save Image As command.
Unfortunately Filter Forge architecture only supports working with videos in the standalone mode — the plug-in can only accept a single still image from the host application.