How to automatically open files downloaded from Safari? [duplicate]

You can add a file extension to the list of "safe" extensions. Once that is done, safari will launch whatever application is associated with that file type.

This is done by creating the file ~/Library/Preferences/com.apple.DownloadAssessment.plist containing the file extension you want opened.

Here is an example, which solves the problem for .torrent files:

<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com-PropertyList-1.0.dtd"> 
<plist version="1.0"> 
<dict> 
 <key>LSRiskCategorySafe</key> 
<dict> 
 <key>LSRiskCategoryExtensions</key> 
<array> 
 <string>torrent</string> 
 </array> 
 </dict> 
 </dict> 
</plist> 

More info here.

If the file exists already, edit it and add the <string>torrent</string> line under the <array>tag

One way is to use Hazel. I tried using it and it worked smoothly. However, Hazel isn't free ($25).

The second solution is to use Automator which is part of Mac OS X.

However, using Automator didn't quite work. Some of the mp4 files did open, but for unknown reason some didn't.

Also I'm not sure if Automator has to open the files as soon as they are downloaded, or there is a time frame which it could take to open them. Maybe some one more experiences with Automator could elaborate on this.