Like in the books, I didn't get the impression that Shae had any choice in the matter. Cersei obviously played a hand in her testimony. The intimate stuff between her and Tyrion, on the other hand, was all her.

Yup. Alfie nailed it, as he always does, and for that alone those scenes weren't a total loss. But that she just left him there, especially after that speech, had me scratching my head.