That's been my experience exactly. Usually one snort/wheeze if they know you're a human and off they go. But, a couple times over the years I've felt like the buck only heard me and was then challenging what he thought was another buck because the loud snorting and blowing went on for 5 or 10 minutes. Both times would have been during the rut. Didn't get a look at either animal unfortunately.I listened to it a few times, and my initial reaction isn’t deer. Sounds more like a bear, deer is normally a snort wheeze or a distinct multiple blows if they wind you
The snort is a warning.I have another video from another place with a bunch of does where the senior one knows I'm around, but not where. She stomps and snorts for a while before leading the girls away.
The snorts at the start and end sounded to my ears exactly like other deer I have heard snort. Its the sound in the middle that sounds exactly like my buck grunt call. First time I've heard it in the wild.