We just finished chapter 1, and sat through the credits and got to the video that leads into chapter 2. It seems we may have missed out part of the cutscene (we saw parts of subtitles for a scene we didn't see over the credits), and certainly the video we did see set in the office aborted before we heard the (presumably) final line or had a chance to read the subtitles.

I assume this isn't normal?

Has the problem happened multiple times, or just once?

You may try setting the performance to something different in the launcher menu to see if that helps. Perhaps the game jumped ahead because it was struggling to load something, but I'm not sure.

Here's a link to a playthrough showing the end of chapter 1, in case you didn't catch all of it.

Thanks for the link - very helpful. We didn't see anything else throughout the game that made us worried we missed something so it was probably a one off. We left it a bit long between savegames to make us want to try replicating it.