Differences among DE2 Boards fo Video in

I'm going to answer by myself

One slight but fundamental difference between the two boards is in the connection ao the 27MHz Clock:

In the older release there is a 27MHz local oscillator that sink both the Video decoder and the FPGA. Moreover the 27MHz LLC signal from the VideoDecoder is also used as input by the FPGA.

In the newest release the local oscillator is a 28MHz oscillator used only by the decoder. The decoder however generate a LLC clock signal at 27 MHZ that sink the FPGA on the same two pins used in the previous version