Apple has quietly released the iMac Graphic FW Update 3.0, saying only that it “fixes a graphics issue that may cause an iMac to hang under certain conditions.” It’s conceivable that this will play a role in resolving the video-related crashes new iMac owners were experiencing under Mac OS X 10.7.0 Lion, though most of those seem to have disappeared with 10.7.1 (see “Video Viewing in Lion Freezes New iMacs,” 4 August 2011). Apple does indicate that this latest firmware update requires Lion, though the company doesn’t say which iMac models are affected. Frankly, though you can download this from Apple’s Web site, we recommend letting Software Update get it for you, since then the download will appear only if it’s relevant for your iMac. As with all firmware updates, be careful not to power down your Mac during the update. (Free, 482 KB)
Extract Directly from Time Machine
Normally you use Time Machine to restore lost data in a file like this: within the Time Machine interface, you go back to the time the file was not yet messed up, and you restore it to replace the file you have now.
You can also elect to keep both, but the restored file takes the name and place of the current one. So, if you have made changes since the backup took place that you would like to keep, they are lost, or you have to mess around a bit to merge changes, rename files, and trash the unwanted one.
As an alternative, you can browse the Time Machine backup volume directly in the Finder like any normal disk, navigate through the chronological backup hierarchy, and find the file which contains the lost content.
Once you've found it, you can open it and the current version of the file side-by-side, and copy information from Time Machine's version of the file into the current one, without losing any content you put in it since the backup was made.