1. v550 video compares to hi8
Hi-8 & DV quality must be more smooth than ANY DC video which are in the forms of lossy-compression, including the mpeg-4 kodak used (others maybe motion-jpeg). For really fast movements, mpeg-1,2,4 will all show "blocks" of video fragments. But I would say, the convenience (no need to A/D conversion and then compression) outweights the minor loss in information. In fact, the object-oriented nature of mpeg-4 will try to stand out the moving objects from it's background, more sharp and pleasing to the eyes (although not a faithful reproduction). Plus for analog Hi-8, it woudl suffered from analog signal loss in addition to A/D convertion "qunatization loss" e.g. if the color space resolution is not enough.
I feel v550 performs very good in implementing mpeg-4 video.
Also, it's the ONLY card-sized DC capable of "optical zoom during video".
2. Samsung video in 256MB SD card.
For the 3 most popular mpeg-4 card-sized DC which samples I've looked at, their video data rates are:
- Samsung i5 - 230KB/sec, optical zoomable, but temporarily mute audio during zoom.
- Casio Z750 - 500KB/sec, only digital zoom video, but "rainbow ripple" problems when shooting densely black/white stripes (see windmill body in Casio z750 gallery sample video)
- Kodak V550 - 500KB/sec, optical zoomable, no muting but some zoom motor audio noise
I feel their video qualities are about equal I would say.
But taking into account, the Samsung audio muting, and the Casio rainbow-ripple & unable to zoom, I think v550 is the best (among these 3).