Yeah, I've done work in iMovie and think it could be done without too much difficulty, so long as no animations are needed (which is not ideal, of course). Part of the reason for having slides big on the screen is that then you can have your face off-camera at times, in case you have to scratch your face or whatever. Being right in front of a high-res camera for 45 mins is not awesome...
Even as someone who does a lot of presenting to audiences, I find recording video of myself speaking all by myself is really awkward. I suppose it's something one can get used to but I find it very hard. My usual approach is to do a quick video introduction to humanize it and then just talk over slides.
