Yes in Final cut pro/express a transition requires a render at some point, you can view it with Control-M (Print) and it will
render and view without a ALT-R to render.
Id bet windows is the same, jst something is happening automatically. Think about it you have a serices of frames in one segment of vide F1 and another series of frames in another segment F2 and the transition is now T1 merging a few frames from the end of
F1 and th ebeginning of F2 - how do we get these frames? The cpu has to generate them somehow, since they are calculations
of T1 = Function( F1 & F2 )
Ed March
http://www.MarchDVD.com