Your source is 8bit YUV; when you convert to AVI with QT Pro, you are converting to 24bit RGB, thus the three times larger size. You definitely do not want to go this route! F4M is just an extension for Windows Media 9 in QT Player and there is not separate player, so I am at a loss as to what you mean here. If you need to convert the QT movie for PC compatibility, convert it to 10bit so that apps that can read and play v210 files will be compatible with it. Media Player Classic and sometimes VirtualDub will work fine with this type of file. VLC is another option. If you need to compress on a PC, then ProCoder and Squeeze should work fine as well.