Hi, I've just had delivered a cheap USB Capture device. Not expecting anything I plugged it into my 4GB PI4 and using Qt V4L2 test utility and to my surprise I got Video from the HDMI input. 1920x1080 t 25fps did prove a bit too much for it as probably expected.
I got playback using VLC on Ubuntu 20.04 on RPI4 on the Plasma desktop but the same options are not showing on the VLC that is available on Manjaro Arm.
Also got playback via Shotcut using Open Other - Video 4 Linux.
Maybe someone might be able to get it working better than my basic knowledge
This is the one I bought