Another way is to install USB chip drivers and access the installed virtual com with the serial class, as it was RS232 interface. If you have already worked with the serial class, then after drivers installation you have a solution ready in a very small time.
I want to be connected to a USB TV BOX, by developing Visual C #, to get the video signal and, through a return to the PIC16F877A RF Wriless,
servo motor and stepping motor control through the application developed by Visual C #.
You might want to take a look at SuiteUSB 3.4 - USB Development tools for Visual Studio - Cypress Semiconductor .
I've seen a few designs where the video data is pumped using a custom protocol which is decoded and displayed on the PC and vendor requests are used to control the other features, like in this case servo motor and stepping motor control.
I haven't worked with video codec and stuff. The designs that I've seen used to have custom library to handle the conversion of raw data to video.
The protocol would be constantly pumping data from the device using the Begindataxfer/waitforxfer/Finishdataxfer API of SuiteUSB then pass on the data to the custom library which would process the data and display as a image.