Screen test scene was misleading

Flat out misleading actually. Watch the actual screen test on youtube. Not a fraction as creepy as the movie version.

I am sure Hitchcock was obsessed with her and my theory is that he was more attracted to Grace Kelly but she was too big for him to try to mess with. So he took it out on Tippi. But how can we trust to what extent based on Tippi Hedren's recollection of stuff we can already see?