QuickTime file sizes after transforming video size

Resetting the dimensions of a QuickTime movie from the properties inspector does NOT actually change the movie's size. It merely scales the size at which it will display in the QT Player. In order to reduce the file size, you must export it as a new movie, applying smaller dimensions, perhaps at a slower frame rate, using appropriate video and audio codecs. In order to do this from QuickTime, you need to buy the Pro version - which is $30 extremely well spent, in my view - considering the vast amount of functionality you unlock.

In my opinion QT pro has no real ability to compress the file size of a video. Other than converting to a AVI file and then using Movie Maker to covert it to a WMV

This is simply not true. QuickTime Pro for Mac and Windows contains numerous exporting options which will reduce the file size of the original content - by a substantial amount, under certain conditions using the H.264 codec. There are also options for specifying other codecs, like MP4 - and media file types like AVI and JPG.

I'll take you through one real-world example here - but there are many more.

Let's assume that a user wants to take a movie file captured from a FireWire camera and distribute it as web-friendly video and audio.

First, the starting movie has to be opened using QuickTIme Pro. On Windows machines, most movies imported from digital camcorders and edited using consumer-grade video editing applications are formatted as "AVI" containers. If you just double-click an AVI file on a windows machine, the default action is for the file to open in Windows Media Player, which does NOT have much exporting functionality. There are several ways to bypass the default action, but the simplest one is this: open QuickTime Pro application first - then use QT's "File" menu to open the media.

Next, use the "export" command, which is under the "file" menu in QT's menu bar. Here, the most common selection (at least for WIndows users) will be to select the option "export to QuickTime movie". For most internet and mobile device delivery, you will want to use the H.264 video codec. The advanced options tabs in the export areas is where the software gives you control over the frame size, the compression ratio, the frame rate, the key frame rate, and the target bandwidth.

Remember that ".MOV" is the default file type extension that identifies QuickTime exclusively. All other video and audio file extensions could cause the media to open in some other player unless you specify it to open in QuickTime. Conversely, an exported, compressed movie cannot be saved by QuickTime Pro in any format other than ".MOV". If you need it to be an "AVI", you will have to re-export the file to the AVI format, after resizing and compression.

I am a true-blue Mac user, so I confess to being somewhat unfamiliar with quirks of QT for Windows - but I tested the exporting example described above using QuickTIme Pro on a Vista Virtual machine running on my PowerBook,

Just to add another voice to this, QuickTime Pro does indeed compress video to many different formats... H.264 for newer computers/devices and even has the capability to save as older formats for use with much older computers.

I regularly compress Multi-gigabyte files to 200 megs or less.