Their discover movie API can search by cast member, but it expects an ID rather than a name:

I think for this to work as a Spice we need an API that allows keyword search for the person's name.
posted by laouji 4 years and 2 months ago Link

Oh... I didn´t know that. Well If I find another source site I´ll tell you.
posted by sebasorribas Community Leader4 years and 2 months ago Link