To use a VK Video Downloader, you will typically need to download and install the software on your device. Once it is installed, you can open the VK Video Downloader and follow the prompts to download videos from VK. This may involve copying the link to the video you want to download, pasting it into the VK Video Downloader, and selecting your preferred download options. The VK Video Downloader will then download the video to your device or computer, and you can access it from the designated download folder or location.