To begin, you will need to find your visual footage of choice for editing. One of the ways this can be achieved is by downloading videos from YouTube. To do this, begin by highlighting the section in front of the youtube url and replacing it with pwn (so it reads pwnyoutube.com).
This will direct you to Deturl.com. Many of the downloading options are unreliable, so be sure to only click on File2HD (preferably in a browser like Chrome that helps prevent unwanted pop-ups as an additional precaution).
Once here, check the terms and service box and select Movies, and then click the Get Files button (ignore any other buttons, no matter how flashy).
Then click on the highest quality file to download your YouTube video.
This video can then by added to your video-editing software of choice. Place the video on your timeline, mute the video, and then add your chosen song.
Publish your video, and voila!