With Safari 5 in Lion, I used the Activity window to save video files.
Safari 6 has no Activity window.
With Mountain Lion, what is the best way to replicate what I could do before?
The Activity Window is gone in Safari 6, but you can get most of the functionality with the Page Resources window of Web Inspector.
To enable that, go to Safari's preferences, and on the Advanced tab, check Show Develop menu in menu bar:
Then you can view the page's resources by clicking Show Page Resources… in the Develop menu, or pressing ⌥⌘A.
That will give you a window with a sidebar similar to this one (which I took from a Youtube page):
It groups things a bit differently than the old activity window, but it should display all the same things. FLV files should be in the Other folder, and you can use the search bar at the bottom to filter for certain strings.
Alternatively, you may be interested in the ClickToPlugin Safari extension, which can do HTML5 replacement of a lot of Flash web video, and in most cases gives you the option to download the file directly just by right-clicking on the video.
Double-click the resource for the video:
Focus the location bar and press option-return. (Command-S doesn't save the complete file.)
Another way to download YouTube videos is to use youtube-dl:
brew install youtube-dl youtube-dl https://www.youtube.com/watch?v=$id
youtube-dl includes the title and ID of the video in the filename by default. It also works with other video sharing sites, and for example it downloads all parts of videos at twitch.tv that are served as multiple resources.
YouTube Options is a Safari extension that shows Download Options -- WebM, MP4, FLV, 3GP, 3D -- right beneath the video.
Available for Chrome and Opera too.
There's a great application called Jaksta that I use that makes it really easy to download all kinds of media from the web. All you have to do is open Jaksta, then go to Safari and play any video or music you want. Jaksta then downloads the file and converts it automatically. Here's a review of Jaksta from MacNews:
Jaksta supports just about all streaming formats and protocols (including FLV, HTTP, RTMP, IceCast, WMV, ASF, MP3, MP4, SWF, etc.), which means it can capture video from thousands of web sites including YouTube and Facebook. What's more, because of Jaksta’s powerful audio-capturing capabilities, customers can download streaming audio from their favorite music and radio sites.
In addition to allowing Mac users to save their favorite videos, songs, and radio programs, Jaksta can automatically convert the downloaded files to a variety of devices. For example, you can save files as QuickTime for the iPod, iPhone, iPad, and Apple TV, as well as import 'em into iTunes. A drop-down menu lets you choose the conversion method you want.
Jaksta can automatically convert captured media files to other formats. The default setting is Default Conversion. This is best if you’d like everything that you download to be easily playable on your Mac. For example, it converts downloaded FLV’s to .mov files that play perfectly in QuickTime.
Here's a description from the Jaksta website:
Jaksta for Mac is easy to use: just open Jaksta, then play the video, music or audio you’d like to capture. You will find that your media is recorded up to ten times faster than playback speed, since Jaksta is grabbing files directly from the web site where they are hosted. This downloading technique means that the quality of the recorded files are perfect copies of the original.
Anyway, I highly recommend Jaksta (and I'm not affiliated with them in any way).
I use and like many of the Safari extensions for flv/youtube/html5 etc. But a more general solution for the missing activity monitor list is provided by hetima with SafariStand
The easiest way to download flv files on most sites is to use click2plugin safari extension