Video Out through USB (or other means)
Your bandwidth requirement is wayyyy beyond USB2 (by a factor of 4-5x).  Unless your images have some special features you can take advantage of, lossless compression is only going to get you a 50% (ish) improvement, so that's not going to work.

You have to either increase your available bandwidth (USB3) or reduce the bandwidth requirement (ie resolution, frame rate, bit depth or some combination).

Regarding the FPGA->USB interface, if you want something easy to get going, try Opal Kelly's boards - they have done the USB3/FPGA interfacing bit for you and you can concentrate on the bit that interests you.  (I have no connection with OK other than as a happy user of their stuff.)

Otherwise, you need a micro with the USB interface on it and some FIFO-like hardware+DMA engine so that the micro is (as you say) only supervising the data transfers.  Cypress make some.  FTDI also (although they are micros, you don't have to touch the innards, you can pretend they are a FIFO and the data 'magically' appears at the PC).