In contrast what the other comment said, I see quite some historic importance in this little clip - I took the first sentence to hint at the fact that Anny Ondra spoke English with German/Czech accent (and maybe Hitch wanted to demonstrate it to her).
This was no problem in silent movies, but Blackmail was switched to "talkie" in the midst of its making, so it was decided to have Joan Barry dub Anny - in real time, as was necessary then. Still, one often sees that Anny's lip movement's are often out of synch with Joan's voice. So the advent of talkies was the end of Anny's chances in English movies, but she carried on making German-language movies until 1951.
This was no problem in silent movies, but Blackmail was switched to "talkie" in the midst of its making, so it was decided to have Joan Barry dub Anny - in real time, as was necessary then. Still, one often sees that Anny's lip movement's are often out of synch with Joan's voice. So the advent of talkies was the end of Anny's chances in English movies, but she carried on making German-language movies until 1951.