Its not really my place to critique Jumpers or Hunters, but when I was trained to jump/hunt (i'd guess I was more Hunter trained, not Jumper trained) My seat had to be very quiet and not come out of the saddle at all. From the videos, it seems like your seat is very loud and that you were not quite in tune with Bam's rhythm. It stood out to me more than anything else. A close second would be that it seems like something is up with your elbows (my god, I already forgot what it was that I wanted to say about them, LOL) I can remember they just didnt look right to me. It also seems like you are over-two pointing for the most part and didnt have the right angle.
On the bright side, I love how you kept your horse in the canter for the entire course and didn't knock down any poles. Your turns were great as well. They will get even better when your seat improves, because your leg will become much more useful when your booty stabilizes. I love when horses give to leg pressure.. it makes everything so wonderful and neat looking! All in all, you kept Bam in a good frame throughout the entire course as well =)
You are definitely on your way to becoming a great hunter! If anything, ask your instructor to do more practice with flat work coupled with two pointing, leg yielding, and maybe even posting at the canter (fun stuff!!!). Practicing those things are a lot easier when you don't have to worry about going over fences too! =)
May I note, you are very brave for posting videos here. Heck, your braver than me for posting here at all. I don't take critique from strangers/people I don't know in person that well at all. I also tend to misinterprit stuff a lot, which leads to hurt feelings, yadda yadda.. so bravo to you for coming forward to post! =)
You're doing great sweetie!!