I can't really hear anything on the video. It did look like your rabbit had hiccups though. There's really no way for anyone here to be able to tell you for sure what the cause might be, whether it's serious or not. I would say that if it's still occurring, and especially if it's ongoing and not just occurring in specific situations like when your rabbit feels stressed about something, that it's probably a good idea to have an experienced rabbit vet check your rabbit out, as it could be a possible indication of a serious respiratory issue.
What kind of rabbit? Not that I have an answer for you, I'm just curious.
My lop squeaks when she drinks water and my lionhead does this interesting type of quiet squeaky chatter with a specific treat of his, I figure it's his favourite