What size videos are you trying to watch?
Assuming you have jumped through all the formatting and SD card size wickets, there is also a video FILE size that is not documented.
Though the manual says "small" size videos; that is not defined.
I found that "normal" sized MP4 files (500 meg to 1 gig or so) do not play (freeze and stutter/pixelate) but smaller sized MP4 videos (no bigger than 4 or 5 minutes) play just fine.
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