Rated 3 out of 5 stars
Very nice. But there are 2 things that'd make it really useful: to add MP3 and captions, if available.
I can see .tmp (which is .mp3) apart from mp4, webm, flv, 3gp when I grab YouTube links. There are some "YouTube to Mp3 converter" apps or sites, but I prefer all-in-one solution with this extension.
There are other ways to download MP4 but not really for captions and that'd be great.
The extension only gets download URLs from YouTube and YouTube doesn't provide MP3 downloads (it's a video site). I'll consider adding captions support. Thanks for your feedback.