Setting a Default for Video Files in OS X Lion

right click on a file of the type you wish to change, click "get info", towards the bottom change the "open with" to the program you want, then click "change all"

 

Cool tip, thanks for this

 

Directions to change default player to VLC fails

I click on VLC and it automatically returns it to QuickTime.
I've tried every variation I can conceive.
Any hint is welcome, especially if it leads to success.

Actually, let me sound PANICED!
QuickTime has already destroyed half a dozen of my valuable MP4 files beyond repair.
I do not wish to lose any more.

 

Not sure if this will work in your case or not, but…

CTL-click on your file and choose Open With, then choose Other. Choose the application you want to open with then check the Always Open With check box.

Hope that works for you, though it may be tedious to do that with all the files you want to change.

 

Problem still. Unable to change app, or default app.

I saw that the offered solution was much like those given by others before.
Thank you for your response, but I had tried those solutions and they failed.

I have failed to communicate the problem I am experiencing.
Please let me try again. Here is what I see step by step:

1. double-click the lecture folder on my desktop
2. find lecture10.MP4 file
3. ctrl-click the lecture10.MP4 file, choose "Get Info", release ctrl
4. Finder Info window appears
5. click on "Open with" (original controls contents appear)

QuickTime Player.app (control with up/down arrows to the right)
Use this application to open all documents like this one.
Change All... (in a grayed out button)​

6. click on up/down arrows (list appears)

QuickTime Player.app (default) (checked)
VLC.app (2.1.4)
VLC.app (2.1.2)
App Store...
Other...​

7. click on VLC.app (2.1.4) (either one will do)

For a few milliseconds I see VLC.app (2.1.4) appear in place of QuickTime, then
QuickTime replaces VLC.app and the selector is back to original controls contents.
I am unable to change this field in any way I have thought to try.

I hope this explanation helps clarify what I am asking.

How do I change the default app for .MP4 files, given that this way fails?
Is there, maybe, some text file I can modify, or some command-line?