This is not directly related to your problem but I found Safari for Lion to be too heavy for my Mac mini 2.0 GHz having 4 GB of memory presumably because of a process called 'Safari Web content'. So, I switched back to OmniWeb (free) <http://www.omnigroup.com/products/omniweb/download/> which runs faster.
As for YouTube, I'm using a freeware MacTubes <http://macapps.web.infoseek.co.jp/mactubes/index_en.html> to save a movie locally. It allows you to download several mp4 files (not flv) at once.
Kino
On 2011-09-12 [+0900 JST], at 3:50 AM, Žorvaršur Davķšsson wrote:
> If you want to download videos from YouTube using Safari you have to open Safari's Activity window (Command+Option+A) and then double click on the entry where the red arrow is
>
> http://i.min.us/jbkJqzlkJk4dHi.png
>
>
> Since a couple of weeks I must additionally press the *Option key* in order to make this work. Is it just me or did Apple recently change the behavior?
>
>
> Žorvaršur
> OS X 10.6.8
> MacBook Pro 17'