[Utah-astronomy] How to download from YouTube?

Anyone here know how to download a YouTube video? NASA has posted the video of last last week's ceremony but it's nearly two hours long. I'd like to download it and extract just my portion and repost just that. But no idea how to do that. https://www.youtube.com/watch?v=aYy_I3gNm6c&feature=youtu.be Help? patrick