First, what are you setting register 00h to? Above you imply 00h = 01h which is selecting s-video I believe.
Regarding the lack of interrupt...
When you are about to connect a PAL camera how is the DM6467 configured? Do you force the DM to PAL mode or do you leave it in NTSC mode until you know you have a camera connected?
My guess is that if you are configuring the DM for PAL and have the TVP in auto-switch mode then obviously the TVP cannot know ahead of time what format camera will be connected, so will send blank video of the previously determined format, which initially would default to NTSC.
Now, NTSC frames are smaller than PAL so the DM will never receive a complete PAL frame, hence never trigger a frame complete interrupt.
If you know ahead of time what format you will be receiving then you can force the TVP to that format so that it will send blank video frames at that resolution.
Alternatively you could try momentarily forcing to PAL then back to auto switch so that when a camera of any format is connected it will switch to that format. In this case though it would 'default' to sending the larger PAL frames which should trigger DM interrupts regardless of the DM being configured for NTSC or PAL.
The other solution might be to either use status change interrupts or polling to check the TVP format then make sure that the DM is configured to the same format.
Hope this helps.
BR,
Steve