APWeb seems to be using a system-id = 67 and component-id = 72 when sending REQUEST_DATA_STREAM messages.
I think it would be better to use a system-id of 1 to match the default used by most vehicles and component-id of perhaps 242 (one higher than MAV_COMP_ID_UART_BRIDGE).
The defaults used now are strangely exactly the same system-id and component-id as used by the SToRM32 mavlink enabled gimbal.