By default, qemu will ignore the presence of hardware virtualization capabilities. To quote the online documentation:
Depending on the target architecture, kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used.
tcg" refers to the built-in "Tiny Code Generator" that is used to (slowly) emulate the guest CPU in software. The Alpine Linux live disc used for demonstration in the video you linked is lightweight enough to boot quickly even without assistance from hardware virtualization. The Ubuntu image you're trying to boot is a lot heavier, and personally, I'm surprised it even started within ten minutes. Also note that guest code running under
tcg is assumed to be trusted, so I wouldn't recommend relying on qemu to contain malicious code in this mode.
Since the host platform in question is Windows, the
whpx accelerator will allow the emulator to use hardware virtualization. Downloads for the HAXM hypervisor are available here. Instructions for enabling the Windows Hypervisor Platform are here. Once one or the other is enabled, telling the emulator to use VT-x through HAXM or the Windows Hypervisor Platform with
-accel hax or
-accel whpx should result in a noticeable speedup.
qemu is inherently complex, and even the individuals who use it on a regular basis prefer to interact with an abstraction layer such as libvirt instead of driving the emulator by hand.
The alternative suggested by @user202729, to use a different virtualization package such as VirtualBox, is probably more straightforward than messing with qemu since other software products are "faster" in the sense that they can be installed and configured by the user in less time.