Hi Andrew,
The general answer is that the video’s are copyright of the BAA and watching them is considered a benefit of being a member, in the same way as viewing the Journal online. The end of each video has a copyright message. Also note that sharing a link to a video does not allow non-members to watch it. You have to be logged in to see beyond the first 2 minutes.
Of course your own PowerPoint presentation remains yours to do with as you wish.
Best wishes,
Andy