When you stumble across a movie on YouTube that you would like to download it is often very problematic.

However, with this extension it is easy and intuitive. Use the provided drop down (embedded in the YouTube page, right below the movie) and select the quality. Then you just have to tell where to save it and after a while (seconds to minutes, depending on the size and whether it has to be re-coded) you have it.

You can even decide to download - say - a music video as a MP3 in various qualities.

I use the PRO version for which you have to pay a little, but with it you are able to download in the highest quality available. Since this requires some muxing on external servers the price is both fair and modest.

I can only recommend this add-on.