Because YouTube uses Adaptive Bitrate Streaming (DASH), these are stored separately to allow the video to switch quality without interrupting the audio. Consequently, a direct "single file" download link for 1080p60 does not exist natively. Any tool that offers this must perform a background process of .
Here is a detailed write-up on the best methods to achieve this, ranging from user-friendly software to command-line tools. youtube download 1080p60
Use "Video DownloadHelper" (available on Firefox and Chrome). youtube download 1080p60