“Now you guys use your COVID hoax, to like, set a checkpoint up to take over the parks and start charging?” Mr Jones can be heard shouting at the teenagers, who appear to be volunteers.
The park re-opened to the public on Monday but requires attendees to book a reservation, a move aimed at preventing large gatherings, helping to limit coronavirus transmission.
But Jones, who was in April issued a warning by the US Food & Drug Administration for pedalling fake cures for the virus, said the new rules are "unconstitutional".
He claimed his wife had visited on Monday but was refused entry.
"This is an illegal power grab of the people's Greenbelt, and it is time to free Austin," Jones, who is not wearing a mask, rants at the teenagers, who don't appear to pay him much attention.
Jones then singles out a boy for wearing a face mask. "Who are you, masked man?" he says.
The boy replies: "I'm a lifeguard for Barton Springs".
Alex Jones is a sad and lonely man. pic.twitter.com/P8ZvRpIJYA— Bradley P. Moss (@BradMossEsq)August 12, 2020
"You're a lifeguard, for Barton Springs, now part of the criminal power grab," Jones shouts back.
"This is outrageous criminal activity. This is the seizure of the infrastructure of Austin."
Jones was widely criticised online for the stunt, video of which has been viewed more than 7 million times.
National security lawyer Bradley P. Moss branded Jones "a sad and lonely man" in a post on Twitter.
ProPublica journalist wrote: "I imagine showing up at a park and harassing some teens with a bull horn and having those teens ignore you and then laugh is pretty humbling even if you are Alex Jones."
Stand-up comedian Patton Oswalt quipped: "Imagine being Alex Jones and this is the life you’re living. Yelling through a bullhorn at disinterested teenagers."
In 2018, Jones's InfoWars show, which frequently promoted misinformation and conspiracies, was removed from a number platforms, including Spotify, Stitcher and Apple.
He has also been sued by a number of Sandy Hook families after claiming the elementary school shooting was 'fake'.