Uncomfortable

Last night John and I went to his sister's house for dinner.  John's youngest (21 years old) and John's mother were also there.  Dinner was very nice and I really like John's family.  John's sister just recently retired so she is going through her house and founds old movies of the family. 

Well, everybody decides that they want to watch a film of John's youngest when he was about 4 when he first learned to swim.  They were all at the time share at Cocoa Beach and it was nice to see John's boys when they were young and even to see John young.  The uncomfortable part was that John was married at the time and just watching the interaction of the family unit just seemed awkward to me.  Also, it was filmed at the same timeshare that John currently owns and we just visited earlier this month.  I sat there and watched the film, but just felt weird the whole time like I was spying on John and his ex or something.  I found myself comparing how he treated her as to how he treats me, and that whole thing. 

Looking back, I probably should have excused myself from the room and gone to sit by the pool by myself or something.  But, of course, I was concerned that I would be considered rude if I did that.  But, I am thinking that they were rude to show the film with me there.  I don't know.  The whole situation was just weird all around.  Later I did tell John that it was weird to watch the movie and he agreed.  I can't imagine it was real comfortable for him either. 

How would you have handled that?  And am I just making a mountain out of a molehill or what?