People who haven't been to Yellowstone in the last 10-15 years always ask us if we see any bears when we go. I remember when it was nearly impossible to see a bear in the park, but those days are over. Each trip we see 15-20 bears, and we don't do anything special. (This 15-20 does count the sow and her 2 cubs we saw 3 days in a row as "9.")
Though we have had a lot of great bear sightings, including seeing cubs inside of 20 feet a few years ago, this video shows my favorite bear sighting of the trip from this year:
Thanks to Natalie for the video and editing
By the way, though we counted 51 different species in the park (including birds), none of them were moose. Don't go to Yellowstone to see moose. We haven't seen any in our last 2 trips. This year the ranger told us there are only 200 left in the park. Go to the Tetons to see moose.