play blu-ray disk on a 576i display

i had a little tv, must have bin 15" lol i got a 23" off my grandad, non hd with the same 576i display, i got a free bru-ray movie from sony(casino royal 007) i tryed playin it on my 15" tv and it played in black and white, i though wel thats normal coz its a hd dvd, but wen i played it on my 23" tv(non hd) it played in colour with sound but it was a bit pixelated coz of the qaulity of the dvd is much richer than the tv, but its still played.... normal or a sony firmware mistake? as this already bin discovered?