After you select Download, you enter the interface as below.
There are three ways to download videos:
1. Open Safari( Firefox or Chrome) to browse the video you want to download. When there is a Download button 
on the top of the video, click it and the video will be added to the Downloading list. Also you can download the Youtube video by resolution.
2. Copy the URL of Video and then click Paste URL button
. The video will start to be downloaded. Or you can choose Downloading>Paste URL on the top menu. The program will download the highest quality video automatically.
3. Drag the URL of the video you are playing to Ultimate icon on Dock or the interface of Video Converter Ultimate, and the video will start to be downloaded.