I think I know what you mean. I created a similar video. However, I went about it completely different. I wanted to video someone giving a Power Point presentation. The best quality came from having the person give the presentation infront of a blue screen. I then used screen capture software to capture the Power Point presentation. I then put it up behind the person. This makes for sharp, bright video image behind the person. Maybe it is still possible for you to accomplish this, if you have access to the image on the screen.
I made my own camera flash that I use as a transition at times when I am “capturing” a frame from video and holding it as a still.
I used the lens flare combined with a white starburst made in Photoshop. I keyframe the size from a small point, to large enough to cover the entire frame. I also keyframe the brightness of the lens flare. Then sycle it all back down again. This all takes place in less than 1/2 sec. I then add a wav file of a camera sound. It comes off pretty realistic.
I created a different, smaller 320 x 240 png sequence in in 3ds Max, on a didfferent computer. Then tried to import the sequence into AE on the different computer. I could get all the way to 580 files in the sequence. It would not accept 581 or anything above.?.
It looks like I may be resorting to importing these sequences in sections.
Use the color selector located on the option bar just below the menu bar. This will only be active when you have the shape tool selected. You could rasterize it. But, you will loose your vector shape.