ここに JPEG のエクステンションがあったよ。
http://www.shine.net.au/plugins/

Picture Object V1.10
A new version of the Picture Object that loads JPEG files.
http://www.shine.net.au/plugins/files/mmf/Picture_Object_V110.exe

Active Picture Object
Identical to the Picture object, but you can move, resize and rotate the picture at runtime. It supports also transparency
http://www.clickteam.com/~webftp/files/Multimedia_Fusion/Extensions/KcPicA.exe