The “magnets” screen grab (looks like you also transcribe Feynman) is 1194x908
That is resized by the API to 1010x768.
It may be that the vision model doesn’t like black in the resulting four tiles and the extra fill.
Sending at under 512x512 and/or setting API quality parameter to “low” may make these problems go away, especially when source is SD video that is under 640x480.