Heathenx, thanks; when I figured out it was the 264 codec I added Perian to my codec supplies and can load your tutorials now but they are just too darn big for my system to play them comfortably; I lose frames, which is horrible when you're trying to follow the mouse actions. So I've downsized the two tuts to 640x480 Quicktime files which I can play better; the quality is still good enough to see what you're doing. It must be nice to have such a fast system.

However, the .flv files play back much, much better - thanks for giving the pointer to that page. They are also smaller than my Quicktime movies, which is nice. I will spend some time with them tomorrow morning.
It looks like what I'm trying to do can probably be done but I suspect that when the application is more mature it will be a lot easier. The exercise of working in an unfamiliar app is interesting, though so I'll stay with it.
EarlyBlake, it's not the Interpolate effect I'm having trouble with so much as the Perspective effect. The Guide blandly tells you to create a quadrilateral but there's no mention of what that means and the index only shows that word in the section I'm talking about - it's recursive but not helpful. Perhaps it's described elsewhere and just never made it into the index, but I read the whole Perspective section several times. [...clicking links...]Ah, that non-video tutorial you've linked to looks interesting, but I'm not sure about that box I'm supposed to create with the four nodes. Can I just draw it with a Bezier line? All the writing on this assumes something that I plainly don't know. Anyway, if I do that and then select it and then select my text and then apply the Perspective effect I always get this error message:
Traceback (most recent call last):
File "Contents/Resources/extensions/perspective.py", line 127, in ?
e.affect()
File "/Volumes/Work/ Graphics Apps/Inkscape/Inkscape.app/Contents/Resources/extensions/inkex.py", line 154, in affect
self.effect()
File "Contents/Resources/extensions/perspective.py", line 80, in effect
solmatrix[i][0] = sp[i][0]
UnboundLocalError: local variable 'sp' referenced before assignment