TESSERACT SOFTWARE  I have a MacBook Pro with OS 10.5.1 and I can't duplicate your issue. When it immediately shuts down, do you mean the computer all of a sudden is off, or do you mean that the OS does the shutdown procedure?

You could try downloading Flash Video Downloader 2 again and installing it again. Perhaps it somehow got corrupted.   
(Version 2.0)

PETRSC  Yes it shuts down all of a sudden. No warning just shut down. It does in both modes - battery and power. I will uninstall the current version, download it and install again. See what happens. :-)

Otherwise it's great app!  
(Version 2.0)

WOLFEATSWORLD  Exact same thing happend to me on my 24" iMac !!

Weirdest thing I ever saw! (I'm running 10.4.10)

I tried it 5 times in a row-and it did the same thing!  
(Version 2.0.1)

SCRIVENS  Go into Preferences and turn off "Shut Down When Finished" .  
(Version 2.0.1)

TESSERACT SOFTWARE  Scrivens tip from the previous reply is for if your computer is shutting down after you finish downloading video(s). From what I understand, its shutting down when you start the application?

For now, we can try a workaround (which will also help me to figure out what is happening).

1. Open a program such as TextEdit and create a new document

2. Write some text (anything) in the document but don't save it

3. Open Flash Video Downloader 2. If it tries to shut down the computer the proper way, TextEdit should ask you if you want to save the document before you quit.

4. Click the cancel button and OS X should tell you that the shutdown was interrupted.

Does that happen? Or does it shutdown anyways?

I'm not sure what could be causing Flash Video Downloader 2 to shutdown your computer on startup, it can only do it when finishing a download, and it uses an applescript command which can be interrupted as described above.

You can use the above as a workaround, if it works. If not, please do the following

1. Open Flash Video Downloader 2 (which will shutdown the computer if you're having this issue).

2. Turn the computer back on and open the Console application ( It's in the Applications/Utilities folder)

3. Click show Log List and a list of logs will be shown on the left side of the window (it may already be there)

4. Select All Messages

5. Then go to File->Save A Copy As...

6. Save a copy of your all messages log (its a .log file) somewhere (e.g. your desktop)

7. Please attach that .log file to an email and send it to tesseractsoftware[at]gmail.com (do NOT post it in this reply on macupdate)

This will hopefully allow me to see any messages that came up from Flash Video Downloader 2, your computer, or some other application before it shuts down. It will give me more insight into what is happening right before your computer shuts down.

I hope that we can figure this out.   
(Version 2.0.1)

PETRSC  yes, open text edit document asks to save the document. if I click CANCEL the apple info dialog appears: "the application text edit canceled the shut down". if there are no open documents like this it shuts down without asking.

I haven't tried the FVD with the "quit after download is finished" check box off. I will try and tell you if it helped.  
(Version 2.0.1)