Because the information in the question is rather scarce, and "some random video" (as @milliways calls it) of more that 20 minutes doesn't help much, we will resort to basic fault searching. Use https://www.raspberrypi.org/documentation/configuration/wireless/access-point-routed.md as reference material.
You state that the network appears on other devices. That would mean that the SSID is broadcasted. Can those other devices connect to the Pi? Can they ping the Pi? If that is the case, the wireless part is OK.
See if the other devices get an IP address. If they don't get an IP address, verify your DHCP configuration. Also verify that on those other devices the default gateway is the IP address of the Pi (that is: the address of the pi on the wlan).
Next, see if the Pi can access the Internet. From the Pi, ping -c3 8.8.8.8. Does that work? If not: check your Internet connection and make it work.
If this all works, then your routing on the Pi may be probably wrong. Check if /etc/sysctl.d/routed-ap.conf has
net.ipv4.ip_forward=1
in it. Depending on your network, you may want the Pi to masquerade (otherwise your Internet router will need to have a static route to your new Wifi subnet via the Pi). Do
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
If that solves the problem, make those rules permanent:
sudo netfilter-persistent save
If this doesn't help, check the logs in /var/log.
