This video from the USA says about itself:
Texas Barn Owls Flap Around on the Porch and Pounce on Prey. June 23, 2015
In this clip we see the oldest owlet head out on to the porch, the second oldest attempts to branch for the first time, but doesn’t quite make it. When the oldest owlet returns a session of pouncing, flapping and prey stealing commences.
It is not unusual for owlets to play by pouncing repeatedly on inanimate objects, or in this case dead prey.
From the Cornell Lab of Ornithology about this:
Oldest Owlet Branches!
The oldest nestling in the Barn Owl box made its first foray outside the opening early in the morning on June 20, about 52 days after hatching. While its siblings looked on seemingly in amazement, the oldest owlet flapped and pranced before returning to the box for the day, and has explored the ledge several times since (watch video).
No other owlets have ventured out yet, but they’re getting braver every day. Even after fledging, the owlets will likely continue to be around the nest box for a few weeks, and will continue to be fed by their parents for another 3-5 weeks. Tune in as the young owls stretch their wings and begin their next adventure!