Not sure if this is any help, but I bought the NEEK (nios eval board) and I am learning the VIP using a demo available in Alterawiki - note: not the 'AN427' demo , but the other one.
I think it is written by one of the Altera dudes, and is probably a good example of how to do what you are trying. It includes most of the VIP modules - used in quite a cool way - live mixing, re-scaling, clipping - absolutely no flickering- amazing. He uses the synchroniser module to make sure things happen at the correct time. On screen display aswell. Hand written pattern generator aswell. You dont need the NEEK to understand it. (written for 9.1, but compiles fine in 10.1)