The Video pane of the Settings dialog (SiteSucker Pro only) provides the following control:
Use this control to specify the preferred resolution of downloaded videos.
YouTube and Vimeo videos are often available in several resolutions. By default, SiteSucker Pro will download the video with the highest resolution. If you would rather download lower resolution videos that are smaller and take up less disk space, you can use this setting. SiteSucker Pro will download the video that has a resolution closest to the preferred resolution.