Since this is actually a Cg shader, it's hard to say for sure.  Is the error
log from the driver available?

Depending on the GLSL version that is used, it is probably these lines:

    float y = yuv.b *255;
    float u = yuv.g *255;
    float v = yuv.r *255;

Many GLSL versions do not do automatic type conversions.  If you change these
to

    float y = yuv.b *255.;
    float u = yuv.g *255.;
    float v = yuv.r *255.;

it should work.  Some of the other constants may need similar treatment.

You could also request a GLSL version that does automatic conversions (1.20 or
later).