I have QT, and Real Player... they do have their uses, but as others have noted, there are better (even though I don't have them), more efficient tools for the job. I'd not bother paying for either QT or RP, not by a long shot.
Now, there may be examples when a version of QT Pro might be useful... it can convert files from one type to another that others just (seemingly) can't, so far as I know. The example I note in this instance was in relation to some native Mac MIDI files from an old computer helicopter sim; I had a forum post on that, actually (I still need to finish the project... just got lost in the to-do list). However, having QT Pro would only help you in that instance if you actually HAD a Mac, as the MIDI files wouldn't play on any other OS, and QT was the only player that I could think of that would play them. Maybe Timidity would help with the issue, but no matter...
...I was able to convert those files, mind you, with a very cool program which I wish they made for Windows called Audio Hijack, which is sort of like a virtual "record from your sound card" option (something I don't believe Macs can do natively). I used retail QT to play the files on a computer, Audio Hijack was linked to record the output from the QT application, and dumped said output as a lossless audio file. I then converted the file format to what I wanted it to be in Audacity.
Moral of the story? You probably don't need to buy anything, and you probably shouldn't either. QT is fine on a Mac, and works well on one, but that's only if you actually have one. Next, if you're doing Audio editing or recording, you probably ought to get Audacity. There are several auido codec plug-ins that will convert just about anything to anything else. However, I think you were noting video concerns, so I'm probably barking up the wrong tree. But, I think this is probably the most fair case for or against QT in the thread to date, so there you go.
