A Slidecast is an animated presentation video with synchronized voice narration. It involves uploading an existing presentation or creating a new one, then uploading an MP3 audio file. The synchronization tool allows leaving the audio unsynchronized or distributing it equally per slide. It can also be used to edit the audio, dragging markers to set start and end points for each slide, with flags indicating the current slide. Green check marks show synchronized slides. Once complete, the work can be saved and published.