This is what Pfizer had to say about the video in a statement on its official company website (passages of particular significance have been bolded by the editor):
Allegations have recently been made related to gain of function and directed evolution research at Pfizer and the company would like to set the record straight.
In the ongoing development of the Pfizer-BioNTech COVID-19 vaccine, Pfizer has not conducted gain of function or directed evolution research.Working with collaborators, we have conducted research where the original SARS-CoV-2 virus has been used to express the spike protein from new variants of concern. This work is undertaken once a new variant of concern has been identified by public health authorities. This research provides a way for us to rapidly assess the ability of an existing vaccine to induce antibodies that neutralize a newly identified variant of concern. We then make this data available through peer reviewed scientific journals and use it as one of the steps to determine whether a vaccine update is required.
Translation: Our "Media & Crisis Teams" are going to be very busy over the next few weeks.