I have done this:

open with

(then click Open) about 4 times now. And yet the last time I clicked on an MP4 file it opened up in Quicktime. It's like OSX is ignoring what I told it to do. When I look at the file with Get Info it says it is an MPEG-4 movie. The default option under "Open With" is Quicktime.

This is aggravating. How do I convince OSX that I really meant it when I checked "Always Open With"?

High Sierra 10.13.4

  • Always open with on the open file window only applies to that file – John Keates Apr 22 '18 at 18:43

Find one mp4 file. Right click, Get Info or Cmd ⌘ I

If not already set, select VLC in Open With, then click Change all...

enter image description here

There's also the old faithful, RCDefaultApp which reports have said no longer works in High Sierra, but I just tested & it appears to.

enter image description here

  • I just did this with 2 mp4s on my computer. One is set to "Open with" VLC and the other is Quicktime. The "Kind" of one is MPEG-4 File and the other is MPEG-4 Movie. I changed it but is there some list of registered file types in OSX? – jcollum Apr 22 '18 at 21:09
  • There's RCDefaultApp which I'd heard no longer worked in High Sierra, but I just tested it & it seems to. – Tetsujin Apr 23 '18 at 6:30
  • ok I'll give that a try tonight or tomorrow night – jcollum Apr 23 '18 at 16:18

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