Greasy Fork

Videos don't download with audio

In Safari, videos don't have audio, just video. Choosing M4V under 480f

That's because 480 (and anything above 720) videos on YouTube are streamed as separate audio and video files. To get video and audio in the same file, you'd either need to use ffmpeg to combine the audio and video files for that quality yourself, or download it in a different quality. Just download as either 720 or 360 and you should be good.

Thanks.

I did put it in the Info page:

On DASH videos (Adaptive Video Streaming)

YouTube now uses adaptive video streaming for 480p and 1080p videos (Oct 2013). What this means is that the video and audio streams are now separate.

They are indicated as M4V and M4A. They have to be downloaded separately and mux'ed before playing. If using ffmpeg:

ffmpeg -i vid.m4v -i vid.m4a -vcodec copy -acodec copy vid.mp4

The filename is always videoplayback. Before saving, select and copy the page title first. Then right-click on the video link, save-as and paste the title. Set the extension to either m4v or m4a to distinguish between video and audio.